@F1world: Four but I'm pushing for a fifth.
Button has started a flying lap on the soft tyre. He's got team-mate Alonso circling right behind him.
@JonathanRubuubi: Promising indeed. At this rate, yes, it's certainly a possibility.
Button passes Grosjean through Turn 13 but the Lotus driver flies past him again on the exit of the corner and Button seems to bail out of the lap. Alonso passes his team-mate on the start/finish straight.
@DonHopings: We don't have access to the live times. We can automatically enter them in but tragically I was only born with one pair of arms so concentrate on the live comms.
@JonathanRubuubi: I think it's definitely designed a good car. The tightly-packaged rear has all the hallmarks of Red Bull (courtesy of Peter Prodromou) but we won't know until the Honda engine is running closer to full power how that translates to downforce etc.
Seems Vettel got some contact from Perez. Seems he slowed down coming down the inside of Turn 1 and Perez, who had already committed to the corner, collected him as he passed.
Doesn't look like Perez knew much about that one. A later radio message suggests Vettel has a brake failure coming into that corner. It also seems he used some rather colourful language about Perez.
Vettel seems a bit irked by that one. That incident will be investigated after the session.
Says Vettel and Perez are being investigated, and usually the first man named is the man being investigated. Mika Salo the race steward this weekend.
"I had a failure. I had a braking failure and f**king Perez took my wing off. Unbelievable!"
-Sebastian Vettel, April 17, 2015
We're into the final five minutes of this session.
Those tweets slightly out of date to my last comment.
I should point out there was a brief red flag for that Vettel moment, while they cleared the damaged part of his front wing from the track.
Rosberg complains about his "diff entry" - his braking differentials - and Mercedes tells him to box as they've seen something on the telemetry they don't like.
Seems Raikkonen and Hamilton are under investigation for "failing to leave the pit lane correctly."
Chequered flag is out now.
Vettel has just told TV he went down to Force India to apologise for that moment.
The cars are peeling back into the pit lane. Rosberg tops the session ahead of Hamilton, but those Ferraris will be hot on the heels of Mercedes tomorrow if the long run pace is anything to go by.
As always, thanks for joining me for this session. We'll be back to do it all again tomorrow, first with FP3 and then with the all-important qualifying under the lights in Sakhir. Please do join me again on Saturday.