Tom Clarkson
BBC Radio 5 live pit-lane reporter in Melbourne

"Esteban Gutierrez needs mileage. In the second test he completed only 45 laps in total. He is not up to speed with the modern F1 car so he just needs to do as much as possible He hasn't raced at Albert Park in two years and he needs to get used to this Haas car. There is a lot going on for him and he just needs mileage to ease his way into the weekend."

Pretty much everyone is waiting for the track to dry out again as bits of blue sky appears between the clouds.

Esteban Gutierrez is finally out for his first run in the Haas, with Fernando Alonso also on the circuit.

They are not the only ones, Max Verstappen is just one of two drivers out on the circuit at the moment and the youngster tests the limits of the circuit as he slides over the kerbs in the Toro Rosso. 

Time is flying by! Forty minutes of the session left, and there are the drivers to have set lap times so far.

1. Daniel Ricciardo 1:32.394

2. Daniil Kvyat 1:34.123

3. Fernando Alonso 1:36.957

4. Kimi Raikkonen 1:40.754

5. Lewis Hamilton 1:40.812

6. Jenson Button 1:43.508

7. Nico Rosberg 1:44.037

8. Jolyon Palmer 1:45.772

9. Kevin Magnussen 1:46.109

Jennie Gow
BBC Radio 5 live pit-lane reporter in Melbourne

Still got problems at Toro Rosso with Carlos Sainz's car. The front of the car is up which normally means they are doing something with fuel. Maybe they are draining fuel out of it at the moment and maybe that is not good news.

Andrew Benson
Chief F1 writer in Melbourne

With all the talk about whether Ferrari can challenge Mercedes for the title, spare a thought for Fernando Alonso, who would have been in the red car if he had not chosen to leave at the end of 2014, having lost faith they would ever be able to produce a fully competitive car. 

He may yet be proved right, of course, but I asked him here whether he would feel a twinge of regret if Vettel was going toe-to-toe with the Mercedes, or even close enough to cause them trouble - circumstances in which, one has to remember, Alonso was only deprived of the title in 2010 and 2012 through bad luck.

“If they win the championship, probably yes,” the Spaniard replied, “because I had a contract last year and this year. So if they win the title this year I will probably feel I could have that opportunity as well. If I was able to drive as good as the champion. But this is a big if.”

After an early appearance, the last I had seen of Fernando Alonso was in the McLaren garage chatting away to Ron Dennis. 

He's out on the circuit now, softs on, and goes third fastest with 1:36.957.

Those cars on the dry tyres are tip toeing round the track to get back to the pits and switch to wet tyres. 

Jolyon Palmer is enjoying himself, though. He had stayed on the intermediates and proceeds to clock his first timed lap with 1:53.585.

Jennie Gow
BBC Radio 5 live pit-lane reporter

"It is starting to rain here in the pitlane - quite heavily as well."

And as I type that, a menacing looking cloud has just rocked up above Albert Park and is starting to dump a fair bit of water on the circuit.

The track is dry so intermediates have been ditched. Daniel Ricciardo, on the medium compound, goes fastest with 1:34.007. Kimi Raikkonen, Sebastian Vettel and Daniil Kvyat also have the white-walled tyre on, while Lewis Hamilton is one of five drivers on softs.

Carlos Sainz is out for the first time in the session...and has his first problem of the session as his Toro Rosso comes to a stop in the pitlane and he has to be wheeled back to the garage.

There's a Ferrari out on the track, with Kimi Raikkonen's first flyer putting him into P1 as he completes a lap in 1:40.754, 0.058 quicker than Nico Rosberg. 

He swiftly heads back in and it is all quiet again.