Button fastest at start of final test

Jenson Button set the fastest time on a close morning in Barcelona, as all ten cars were separated by just two seconds.

In a clear indication of how times in testing can be misleading, Button set his best time on hard tyres having previously been quickest on softs. His headline lap of 1:23.510 came during just 27 laps of running as McLaren worked with what Martin Whitmarsh called a "fairly substantial" update on the MP4-27.

Sergio Perez was second quickest as Sauber completed a series of short runs during the morning session and not using the soft tyres. At one stage Perez was closing on Mark Webber's Red Bull by half a second a lap despite the latter being on soft tyres, but it betrayed a lack of fuel in the Sauber and he eventually brought the session to a slightly early end as another fuel run-out test saw him stop at turn 6 and cause the only red flag of the morning.

Lotus carried out some basic aerodynamic tests in the early part of the morning session before removing the sensors from the car in order to carry out some more extensive running. There appeared to be no further issues with the wishbone which forced the team to withdraw from the previous test, and Grosjean covered 38 laps as he was third fastest. His time of 1:23.959 will have been encouraging, as the team confirmed to ESPNF1 that it would be trying to condense two tests work in to the next four days.

Nico Rosberg was productive for Mercedes, with his best time of 1:23.992 coming during a soft tyre run later in the session, putting him just one thousandth of a second ahead of Webber.

Toro Rosso also had a busy morning as Jean-Eric Vergne completed 61 laps. Having set a best time of 1:24.216 Vergne also focussed on hitting his pit marks after every run. He was less than 0.1s ahead of Paul di Resta who completed some aero work before some more substantial runs later in the session.

Ferrari continued to work on the F2012 with Felipe Massa carrying out constant speed tests before later stints on the hard tyre. The close nature of the session was highlighted by the fact that Massa's time was just 0.8s slower than Button but only good enough for eighth quickest.

Vitaly Petrov was the only man to try the supersofts during the morning session and it saw him improve to within 1.4s of the quickest time. Petrov was a late replacement for the ill Heikki Kovalainen at Lotus, but still managed to complete the most laps with 67, while it was a slow start to the day for Williams as Pastor Maldonado remained in the pits for the early part of the session after completing his installation lap and ended the morning tenth.