Schumacher's Mercedes tops the times - but how fast is it really?
Michael Schumacher responded to concerns about the pace of the new Mercedes by setting the fastest time of the second day of testing at Jerez.
The seven-time champion recorded a lap of one minute 20.352 seconds to head Ferrari's Felipe Massa by 0.061secs.
After a slow start, Jenson Button moved up to third fastest in the new McLaren, ahead of Toro Rosso's Jaime Alguersuari and Red Bull's Mark Webber.
This test is the first time the 2011 McLaren has run against its rivals.
And on Friday the 2009 world champion had his first run in the car after taking over from Lewis Hamilton.
It's been a good first day - on Sunday, I hope we can start to have a crack at seeing what the car really has in it
After running systems checks for most of the morning, Button got progressively faster as the day went on.
His time of 1:21.009 was 0.657secs off Schumacher's fastest.
Button, who hands back over to Hamilton on Saturday before driving again on Sunday, said in a McLaren statement that he had spent the morning getting fitted into the car and getting used to the Kers energy storage and power-boost system.
"I felt a lot more comfortable with the car at the end of the day after we'd played around with a few things in the cockpit. We've made some good progress," Button said.
"And we've tried the different Pirelli tyres - there are big differences across the compound range; not only in terms of lap time, but also with degradation and durability.
"It's going to be fun for racing, I think, and it's what everyone wanted. The TV viewers will certainly know the differences between the tyres.
Button had his first taste of the new McLaren on Friday
"It's been a good first day. On Sunday, I hope we can start to have a crack at seeing what the car really has in it."
Webber set the initial pace early on Friday morning before Schumacher recorded a lap of 1:21.408 seconds to beat the Australian by 0.204secs.
That mark was still 0.7secs slower than Massa's fastest lap on Thursday, a 1:20.709.
But Schumacher then lowered his time further to the 1:20.352 to set the fastest lap of the test so far.
However, Schumacher was relatively downbeat when speaking to BBC Sport on Thursday about the car's pace and said that getting on the podium would be difficult for Mercedes at the start of the season.
And the German legend admitted that he had been running the grippier super-soft tyres, telling reporters: "Obviously that makes us a little bit quicker than some teams that have not tried those tyres."
BBC pit-lane reporter Lee McKenzie, who was in Jerez on Friday, said on the social networking site
: "(Red Bull team boss) Christian Horner in good spirits and says everything going to plan. Hints from those who know that Merc maybe not going so well."
We are moving forward as we should during the testing period but at the same time, we are aware we have to keep pushing
Schumacher said in a team statement on Friday: "It clearly was a productive day, and obviously I am happy about that.
"We were focusing on long runs and being able to produce such a lot of mileage is positive in terms of reliability.
"It also gives us good data for the test days to come and for the developments we are working on.
"We are moving forward as we should during the testing period but at the same time, we are aware we have to keep pushing."
Schumacher, 42, took the car over from team-mate Nico Rosberg, who was 3.2secs off Massa's pace on Thursday and said he had "expected" the car to be off the pace at this stage because it was awaiting a major upgrade before the first race of the season.
All the leading teams will have major upgrades for their cars in time for the first race of the season in Bahrain on 13 March.
Headline lap times from winter testing are notoriously difficult to interpret as teams do not reveal the spec their car is running in.
The Red Bull continues to look like the car to beat
A car's speed can vary by as much as five seconds a lap depending on how much fuel it has on board. Tyres also make a significant difference - and all four of Pirelli's dry-weather compounds are available in Jerez.
Novices Pastor Maldonado and Sergio Perez both had sizeable crashes in the afternoon as they got to grips with F1 and their new cars.
Mexican Perez crashed his Sauber when he lost the rear going into Turn Eight, ripping off the front wheel and wing.
And Venezuelan Maldonado lost control of his Williams at the fast Turn Four, damaging the front and rear wings and the rear suspension.
Eleven of the 12 teams are in Jerez, while Hispania - whose new car will not appear until the final pre-season test in Bahrain a week before the start of the season - preferred to spend some time filming at Monza in Italy.
Robert has been doing a great job. If I can step in until he's better, that would be great
Vitaly Petrov is driving for Renault, who have yet to decide on a replacement for the injured Robert Kubica.
The Pole has
told Gazzetta dello Sport that he is determined to return
this season, and his former BMW Sauber team-mate Nick Heidfeld is the hot favourite to replace him.
The German veteran will drive the Renault on Saturday and team boss Eric Boullier has said that if he impresses the team the drive is his.
Heidfeld told BBC Sport on Friday: "It's not necessarily having to push myself (to impress the team). I will just do my usual job.
"I've been speaking to Renault anyway for the last two years about being involved with the team in some way.
"Robert has been doing a great job. If I can step in until he's better, that would be great.
"I haven't spoken to him directly, but I have sent him a text and I'm very happy that he's on the mend."
Renault are also going to give third driver Bruno Senna some time in the car over the weekend.
Second pre-season test, day two, Jerez de la Frontera:
1 Michael Schumacher (Ger) Mercedes one minute 20.352 seconds
2 Felipe Massa (Brz) Ferrari 1:20.413
3 Jenson Button (GB) McLaren-Mercedes 1:21.009
4 Jaime Alguersuari (Spa) Toro Rosso-Ferrari 1:21.214
5 Mark Webber (Aus) Red Bull-Renault 1:21.613
6 Adrian Sutil (Ger) Force India-Mercedes 1:21.780
7 Sergio Perez (Mex) Sauber-Ferrari 1:21.857
8 Timo Glock (Ger) Virgin-Cosworth 1:22.208
9 Vitaly Petrov (Rus) Renault 1:22.493
10 Pastor Maldonado (Ven) Williams-Cosworth 1:22.591
11 Jarno Trulli (Ita) Lotus-Renault 1:23.216