05:45 Welcome back to AUTOSPORT Live as we approach the qualifying session for the Australian Grand Prix.

After months of testing and two days of practice, now is the time for the true pace of each car and driver to be revealed as they battle it out for grid position ahead of tomorrow's race.

05:46 AUTOSPORT forum members are invited to join the fun throughout the weekend, offering thoughts and opinions as the event unfolds.

• Are we really going to see Williams, Brawn GP and Toyota occupy the front end of the grid?

• Do the other teams have some pace in reserve, or is the order from practice really the jumbled formbook we will see on the grid?

Tell everyone what you think.

Click the SHOW LIVE FORUM link in the red bar at the bottom of your browser window if you'd like to join the debate.

05:48 Wall-to-wall sunshine continues today, and the knock-out qualifying session will take place in excellent conditions.

Visibility could become a minor issue for the drivers in the final part of the session, with the sun beginning to lower in the sky as the day wears on and become a bit more apparent in the drivers' field of vision.

05:50 Earlier today, Nico Rosberg topped the practice times once again in the Williams FW31, with a great, late lap of 1:25.808. Jarno Trulli followed the German in second spot, with Jenson Button third for Brawn GP. Felipe Massa was fourth for Ferrari, with Kazuki Nakajima fifth and Rubens Barrichello sixth.

Massa's Ferrari was the only car in the top six that doesn't feature the disputed design of rear diffuser.

Some notable names were further down the pecking order. McLaren drivers Heikki Kovalainen and Lewis Hamilton were 11th and 12th, Fernando Alonso was well down the field in 17th, and Kimi Raikkonen finished last in the second Ferrari with a technical problem.

Rosberg also tops final Australia practice

05:51 This morning's practice session did not go well for Ferrari's Kimi Raikkonen. He pulled off the circuit after only five laps, suffering problems with the car's hydraulics.

The Ferrari mechanics have been hard at work during the interval, and his car is now repaired ahead of the qualifying session. The cars must be race-ready by this point as they enter parc ferme conditions once the session is underway.

05:53 The qualifying format is one thing that hasn't changed for 2009. Five cars will be eliminated after the first 20-minute period, with the remaining 15 runners battling it out in the next segment for a place in the top-ten shootout.

The scramble to make it in to the final ten-minute decider is likely to be a main talking point today, with the shake-up in the established order giving the potential for high-profile eliminations at the end of Q2.

05:55 Qualifying for the Australian Grand Prix gets underway in five minutes.

05:55 A crowd of 74,500 fans are on hand for this session, which starts unusually late in the day - 5pm local time.

05:58 The track temperature is 32 Celsius and is likely to fall during this session, which may lead to a changing grip level as yet another factor for the teams to consider.

05:58 Down at Brawn GP, Rubens Barrichello is receiving final instructions before he puts his helmet on and climbs aboard the BGP 001, while Virgin Group boss Richard Branson looks on with interest.

06:00 Qualifying is underway at Albert Park.

06:01 All the teams have decided to wait out the opening moments of the session. An Australian GT support race took place between sessions, and no-one wants to clean the track first.

06:01 Giancarlo Fisichella breaks what was a brief silence, and the Italian heads out onto the circuit in the Force India.

06:02 Nico Rosberg and Sebastien Buemi have also driven out of their garages, with more drivers now following them.

06:03 Kovalainen, Massa and Raikkonen head out to make it half of the field out for an early lap.

06:03 Giancarlo Fisichella crosses the line to begin the first flying lap of the qualifying session. Giancarlo is out there with the soft tyre option.

06:04 Fisichella comes through to complete the first timed lap, and it is a 1:28.840.

06:05 Sebastien Bumi goes second to Fisichella, but behind him on the circuit Nico Rosberg flashes past in 1:27.833 to go fastest so far.

06:05 Felipe Massa takes a current second-place time with a 1:28.346 in the Ferrari.

06:06 Adrian Sutil has shot in to second place in the Force India with a 1:28.118. His team-mate Giancarlo Fisichella goes on for a second lap, and the Italian places third with a 1:27.984.

06:07 Kazuki Nakajima now moves to the top of the list with 1:26.752, making it a Williams one-two at the moment.

06:07 Massa continues for another lap, improving to a 1:27.446 as the lapping pack continue to clean up the circuit.

Kimi Raikkonen is up to third with a 1:27.254 as he recovers from the technical problem this morning.

06:08 Rosberg, Buemi and Fisichella have completed their first run, as Jenson Button and Rubens Barrichello begin their first timed laps.

06:08 Kimi Raikkonen tops the order with a 1:26.615.

06:09 Rubens Barrichello completes that tour and he slots in fourth, but is immediately demoted to fifth by Mark Webber.

Fernando Alonso now takes his turn at the top with 1:26.474.

06:10 Jenson Button's first effort only placed him 12th, as his team-mate Barrichello goes fastest of all with a time of 1:26.247.

06:11 Lewis Hamilton makes his first attempt of the day. He clocks a 1:26.454 on the softer tyres to slot in second.

06:11 Jenson Button is now on a much quicker lap, and yes, he vaults up the order from 14th to second place with a 1:26.253.

06:12 The BMW pair of Kubica and Heidfeld are only now starting their first flying laps of the session.

06:13 Rubens Barrichello improves further and is now three-tenths clear of the rest of the field. 1:25.815 for Barrichello.

06:13 Kubica goes 16th with a 1:27.225, with team-mate Heidfeld setting the slowest time.

06:14 All 20 drivers have now set a time in this opening period of qualifying. Jarno Trulli, Robert Kubica, Giancarlo Fisichella, Nelson Piquet and Felipe Massa are in the final five places, and must improve or face elimination.

06:15 Kazuki Nakajima improves his time, setting a 1:26.299 for fourth in the Williams.

06:15 Robert Kubica moves out of the dropzone, into fifth place with 1:26.386.

06:16 Felipe Massa - currently last - is out with the soft tyres, and he moves up 18 positions to second with 1:25.844.

06:17 Kimi Raikkonen is on a much better lap and is fastest in the first and second sectors.

06:18 On the softer tyre, Kimi runs wide in Turn 14, costing him a lot of time - fourth place at the moment.

06:18 The dropzone is now comprised of Bourdais, Kovalainen, Sutil, Trulli and Fisichella. They are all out on the circuit on their final attempts to make it through to round two.

06:19 Australia's Mark Webber is on a charge with the softer tyre. He goes quickest with a 1:25.427.

06:20 Adrian Sutil is the first to show his hand out of the five dropzone drivers. His first sector isn't quick enough despite being his fastest so far in the session. He moves up to 15th place, and will have one last attempt.

06:20 Sebastian Vettel improves to sixth in the other Red Bull.

06:20 The qualifying period has ended. Cars that have already started a lap may complete it.

06:20 Jarno Trulli moves out of the dropzone, into seventh with 1:26.194.

06:20 Giancarlo Fisichella was not fast enough on his final effort and the Italian is eliminated.

06:21 The pair of BMWs both improve their times in the late scramble.

06:21 The first period of qualifying has been completed. The following drivers have been eliminated:

16) Buemi
17) Piquet
18) Fisichella
19) Sutil
20) Bourdais.

06:22 The Brawn pair of Barrichello and Button set late flyers to go one-two as the session ends.

06:23 World champion Lewis Hamilton was extremely close to elimination in that session and finished the segment 15th.

06:23 Sebastien Bourdais apologises to the Toro Rosso team on the radio, agreeing that if he cannot get a quick outlap then his chances are finished, due to not getting enough heat into the tyres.

The Frenchman will start tomorrow's Australian Grand Prix from 20th place on the grid.

06:26 Hamilton escaped elimination by just 0.049s and faces an uphill struggle to make it in to the top-ten shootout.

06:26 The remaining 15 drivers will now reset, and look ahead to the second period of qualifying.

06:27 The qualifying period has started.

06:28 Kimi Raikkonen is the first to leave the pitlane in the Ferrari.

06:29 Massa and the two Toyota drivers Glock and Trulli have also come out onto the track, as Raikkonen rounds Turn 16 and begins his flying lap.

06:30 Lewis Hamilton has a transmission problem with his McLaren and will take no further part in the session.

06:31 Kimi Raikkonen's first effort is a 1:25.380.

06:32 Felipe Massa slots in second with a 1:25.539 on the softer tyre.

06:32 Timo Glock crosses start-finish to top the Ferrari duo. Glock fastest with 1:25.281.

06:33 Rubens Barrichello is now second quickest behind Glock with 1:25.287, but seconds later Jenson Button beats both of them with 1:25.205.

06:34 Mark Webber is now second to Button with 1:25.241. Timo Glock is third and back in the pits, Barrichello is fourth with Raikkonen having dropped to fifth.

06:34 Heikki Kovalainen's first attempt is a 1:25.937, the slowest time set in the segment so far.

06:35 Sebastian Vettel moves to the top of the classification with a lap of 1:25.121, Red Bull Racing are currently first and third.

06:35 The BMW pair are the last to leave the pits for a qualifying attempt.

06:36 Nico Rosberg joins the party in his Williams and goes second after setting a 1:25.123.

06:37 The top ten drivers are all in the pits. Vettel is quickest ahead of Rosberg, Button, Webber, Glock and Rubens Barrichello rounding out the top six.

06:37 Nick Heidfeld clocks a 1:25.635 on the softer tyres, but it is only enough for 11th.

Team-mate Kubica takes third quickest with a 1:25.152.

06:39 Lewis Hamilton as we mentioned, will not be taking any further part in the session. He will start the Australian Grand Prix from 15th position.

The remaining 14 drivers have posted a time on the board. Jarno Trulli, Nick Heidfeld, Kazuki Nakajima and Heikki Kovalainen are in the dropzone and must improve.

06:40 Heikki Kovalainen has just completed a timed lap, but failed to improve his time. The Finn's chances are diminishing, and he remains in 14th place for the moment.

06:40 All the cars except Hamilton's broken McLaren are now on track for a final attempt.

06:41 The field is extremely tight, with a couple of tenths covering the top nine.

06:41 Heikki Kovalainen returns to the pits and will not set another time. The Finn is eliminated.

06:42 Barrichello puts the Brawn GP car back to the top with a 1:24.783 and team-mate Button goes second, just a fraction slower.

06:43 Nick Heidfeld moves out of the dropzone to tenth, dropping Fernando Alonso into 11th spot. Alonso needs to improve on his final attempt, which he is close tocompleting ... he pits. Alonso is out.

06:43 Q2 is now complete in Australia.

06:43 Jarno Trulli improves on his last lap and moves out of the dropzone, into seventh. This drops Heidfeld down to 11th. Heidfeld is also eliminated.

06:44 The second period of qualifying has been completed. The following drivers have been eliminated:

11) Heidfeld
12) Alonso
13) Nakajima
14) Kovalainen
15) Hamilton.

06:44 Late runs for Vettel and Rosberg put them third and fourth quickest in the Q2 order.

06:46 After two fascinating sessions, the field is set for the pole position battle. With the times so close, the outcome of the final ten minutes is far from predictable.

06:48 So the bottom half of the grid for tomorrow's grand prix is decided. The remaining ten drivers will now go again in the final shootout.

They are:

Rubens Barrichello
Jenson Button
Sebastian Vettel
Nico Rosberg
Robert Kubica
Mark Webber
Jarno Trulli
Timo Glock
Felipe Massa
Kimi Raikkonen.

06:50 The battle for pole position is underway.

06:51 Nico Rosberg leads the pack out of the pits.

06:51 Brawn GP drivers Rubens Barrichello and Jenson Button leave the pits.

06:51 Kimi Raikkonen is also out early in the Ferrari.

06:51 Jarno Trulli has come out of the pits in the Toyota.

06:52 Once again these cars have been loaded with race fuel, however this year we are expecting to learn the weight of each car before tomorrow's race.

06:52 Jenson Button crosses the line to begin his flying lap.

06:53 Button runs slightly wide at the exit of Turn 12 but no damage done. But it may hurt his first laptime. He sets a 1:26.600.

06:54 Rubens Barrichello slots into second place with a 1:27.161.

06:54 Nico Rosberg takes third with a 1:28.110 in the Williams.

06:55 Jarno Trulli is fourth behind Rosberg with 1:28.464.

06:55 The Ferraris of Raikkonen and Massa slot in fifth and sixth after the first runs.

06:55 Nico Rosberg improves his time but it is still not enough to catch the Brawn GP front row.

06:56 The two Brawn machines are already back in the pits. A quick change of tyres and they will be the first drivers to make their final assault for the front row.

06:56 The Red Bull pair of Webber and Vettel lock out the second row after their first laps.

06:57 Felipe Massa made that attempt on the harder tyre and reports on the radio that he thinks he has a puncture. His team aren't so sure.

06:57 Toyota drivers Timo Glock and Jarno Trulli have posted the seventh and eighth fastest times at the end of the first run.

06:58 Webber and Vettel pit together and leave with new Super Soft compound tyres.

06:58 Rubens Barrichello and Jenson Button are spaced by a good 30 seconds or more on the track. Barrichello will have the shot for pole, and then Button will shortly follow.

Barrichello starts his final effort now.

06:59 It's a fastest first sector time for Barrichello as he flies round the Albert Park circuit. It is a clean lap so far and he will be very close to Jenson's time.

07:00 The flag is out but there are plenty of laps still to be completed.

07:00 Barrichello crosses the line and moves into provisional pole with a 1:26.505.

07:00 All of the pack are setting faster sector times.

07:01 Robert Kubica takes third away from Rosberg and Glock.

07:01 Button is coming round the final corners of the lap now. Can the Briton do it?

Yes he can! It's a wonderful pole position for Jenson Button in the Brawn Mercedes with a stunning 1:26.202.

07:01 Felipe Massa crosses the line seventh, with team-mate Raikkonen ninth.

07:02 Mark Webber's last run was a 1:27.246 and he tumbled to tenth.

Team-mate Vettel takes third!

07:03 Jenson Button secures pole position for tomorrow's Australian Grand Prix. He is delighted on the team radio as he comes back to the pits. It's a Brawn GP lockout on the front row with Rubens Barrichello in second place.

Sebastian Vettel will start from third place in the Red Bull, with Robert Kubica fourth for BMW.

07:04 Nico Rosberg is fifth and Timo Glock starts from sixth. Felipe Massa is the fastest Ferrari driver in seventh, with Jarno Trulli eighth, Kimi Raikkonen ninth and Mark Webber rounding out the top ten.

07:08 The report and classification on a thrilling session is now available:

Button leads all-Brawn front row in Oz

07:10 Stick with AUTOSPORT throughout the day for all the reaction and analysis from Melbourne.

07:11 What an astounding grid we have for the season-opening Australian Grand Prix.

Brawn GP have locked out the front row of the grid ... it's amazing. From the first tests the team carried out in Barcelona, there was talk that this result could happen.

As the race weekend progressed, the world realised that this wasn't just a winter testing 'fluke'. Brawn GP were serious, and today, they have scored a qualifying performance that will rock the sport. Tomorrow, the points will be awarded, and it will be fascinating to see if either Jenson Button or Rubens Barrichello can win.

Join us tomorrow from 04:30 GMT here on AUTOSPORT Live as we get ready for an amazing Australian Grand Prix.