Ahead of today's opening session, the air temperature is 18 degrees C, while the track temperature is 31 degrees. Though bright there is a lot of cloud and there is a 10% chance of rain.

In terms of updates, Red Bull has a new Front Wing End and Rear Corner, while Mercedes has a revised Floor Edge, Alpine a new Halo and McLaren a new Coke/Engine Cover and Diffuser.

Alfa Romeo has a new Nose Performance, Front Wing and Sidepod Inlet, while AlphaTauri has a new Floor, Floor Fences, Floor Edge and Diffuser and Williams a new Front Wing and Rear Wing Endplate.

There are no updates to the Ferrari, Aston Martin or Haas.

The lights go green and Sainz leads the way, followed by Zhou, Ocon, Albon, de Vries and, local hero, Piastri.

As more drivers head out it is the hards and mediums that are in use.

The cameras cut to Daniel Ricciardo who is on the Red Bull pit-wall.

Piastri reports that his dash is "very dull". Despite this, the Australian is quickest of the first wave, crossing the line at 22.740.

Perez subsequently posts a 20.267, as Verstappen goes second, ahead of Russell and Hamilton.

"I'm bottoming so much I can't see," reports Sargeant as Hamilton warns that he too has "got bouncing".

A 19.332 sees Verstappen go top as Norris remains the only driver yet to make an appearance. However, McLaren is at pains to clarify that there is no issue with his car and that they are only making set-up changes.

Carrying too much speed, Magnussen makes full use of the gravel trap at Turn 3.

A big snap of oversteer at Turn 9 for Hamilton causes a sharp intake of breath.

Perez improves with a 19.293 as Gasly posts a 20.032 to go fourth.

Stroll is currently third (19.766), while teammate Alonso has yet to post a representative time.

Switching to the softs, the first driver to do so, Verstappen posts a 19.278, at which point Perez urges: "Let's get on to the softs".

Ocon is another driver complaining about the bouncing.

Alonso improves to 14th with a 20.990 as Russell and Piastri make the switch to softs.

With 35 minutes remaining, Norris finally heads out, on mediums.

Verstappen isn't entirely happy with the balance of his car.

De Vries improves to sixth with a 19.933 on the red-banded rubber.

Norris' first representative lap sees the Briton go 16th (21.246), as teammate Piastri posts a 19.777 to go fifth.

Albon complains of "rear locking everywhere".

On the softs, Leclerc goes third (19.378) and Sainz fourth (19.687).

Interestingly, the softs don't appear to be that much quicker than the mediums.

Perez runs wide at Turn 4, kicking up a cloud of dust in the process. Previously, teammate Verstappen had complained of his rear brakes "dragging".

Stroll improves to fifth (19.766) and Alonso eighth (19.780).

Tsunoda carries far too much speed into Turn 4 and loses the rear end of his Alpha sending his spinning backwards over the gravel. He does well to keep it out of the barriers.

It's only FP1 but we are already seeing issues with traffic.

The stewards report that both Haas drivers and their counterparts at Alfa Romeo have taken on new engines.

As Hamilton complains of "dangerous driving" by de Vries, Magnussen is the latest to have a moment.

"Man these guys, what are they doing," complains Zhou, "I nearly crashed into them, the Mercedes and the Red Bull."

With just over 22 minutes remaining the session is red-flagged. Seemingly this is due to the GPS system being down.

With no GPS, the teams are unable to warn their drivers about traffic and who is on a fast lap etc... as proven when Tsunoda almost trips up over a very slow Ferrari. Indeed, replay shows Leclerc being urgently warned: "Watch the mirrors, GPS not working!"

"There is a GPS issue currently," confirms the FIA, "and the red flag is necessary for safety reasons with teams not being able to monitor car position and closing speed."

The session resumes with 14 minutes remaining.

Verstappen is first out, followed by Sargeant, Albon, Hamilton and Alonso.

Again there is a mix of tyres with all three compounds in use. Some teams appear to want to use the time remaining for longer runs while others are focussing on their soft runs.

Norris goes sixth (19.536) on the softs, having been quickest of all in S3.

All bar Leclerc and Tsunoda are on track, the Japanese unlikely to reappear following his earlier off.

Verstappen spins at Turn 4, bringing out the yellows.

One gets the feeling that track limits are going to have an impact this weekend.

Once again the session is red-flagged as Sargeant loses power and stops on track. "My car's shut off," he reports.

With just under 4 minutes remaining, Race Control advises that the session will not resume.

Verstappen is quickest, ahead of Hamilton, Perez, Alonso, Leclerc, Sainz, Norris, Gasly, Russell and Stroll.

Albon is eleventh, ahead of Piastri, Hulkenberg, de Vries, Sargeant, Ocon, Tsunoda, Bottas, Zhou and Magnussen.

Check out our Friday gallery from Melbourne here.