Button sends out warning with fine run in practice

Jenson Button set what was only the fourth-fastest time overall yesterday as practice began for tomorrow's Spanish Grand Prix, but the fact that when he set it during the morning session it was more than three-tenths faster than his closest rival suggested that his Brawn car could still enjoy an advantage tomorrow afternoon.

Williams' Nico Rosberg and Kazuki Nakajima, and Fernando Alonso in his Renault, all shaved time from Button's benchmark in the afternoon, but the general feeling was that the first session was the one in which more people were running close to qualifying trim rather than focusing on race preparation, and then Button had no peer as he swiped fastest time away from Toyota's Jarno Trulli with a lap of 1m 21.799s that eclipsed the Italian's best by 0.355s.

It is unusual for such things to matter on a Friday, traditionally a time when there are so many different programmes of preparation that the times are all but inconclusive, but yesterday was special. Since testing was banned once the 2009 season got under way, as part of the package of new regulations, teams have no other opportunity to try out modifications. With four fly-away races, and only McLaren, Renault and Force India managing to incorporate significant updates during that period, the majority of teams have been working towards the Spanish race to upgrade their cars.

Ferrari and BMW-Sauber have major changes to evaluate before the race as they seek to revive their world championship campaigns. Ferrari's Felipe Massa said: "We have done a good job over the past weeks and the car has improved, but of course the others haven't been standing around with their hands in their pockets."

Lewis Hamilton, only 13th, said he expected a hard race. "That is our true pace, as you just saw," he admitted. "It is going to be a tough one for sure."

Button said: "The balance of my car hasn't been quite right today with our new aero upgrade fitted. We have been struggling for grip which was a little frustrating, but we believe that we have identified the reasons."

Spanish GP details

*First practice session

1 J Button (GB) Brawn-Mercedes 1 min 21.799;

2 J Trulli (It) Toyota 1:22.154;

3 R Kubica (Pol) BMW-Sauber 1:22.221;

4 N Heidfeld (Ger) BMW-Sauber 1:22.658;

5 K Nakajima (Japan) Williams-Toyota 1:22.659;

6 N Rosberg (Ger) Williams-Toyota 1:22.667;

7 N Piquet (Br) Renault 1:22.753;

8 T Glock (Ger) Toyota 1:22.828;

9 F Massa (Br) Ferrari 1:22.855;

10 R Barrichello (Br) Brawn-Mercedes 1:22.859

11 K Raikkonen (Fin) Ferrari 1:22.873; 12 M Webber (Australia) Red Bull-Renault 1:22.934; 13 S Vettel (Ger) Red Bull-Renault 1:22.959; 14 L Hamilton (GB) McLaren-Mercedes 1:23.077; 15 S Bourdais (Fr) Toro Rosso 1:23.088; 16 G Fisichella (It) Force India-Mercedes 1:23.089; 17 F Alonso (Sp) Renault 1:23.157; 18 S Buemi (Swit) Toro Rosso-Ferrai 1:23.185; 19 H Kovalainen (Fin) McLaren-Mercedes 1:23.522; 20 A Sutil (Ger) Force India-Mercedes 1:23.536.

*Second session

1 Rosberg 1 min 21.588;

2 Nakajima 1:21.740;

3 Alonso 1:21.781;

4 Barrichello 1:21.843;

5 1:22.027;

6 Button 1:22.052;

7 Vettel 1:22.082;

8 Piquet 1:22.349;

9 Buemi 1:22.571;

10 K Raikkonen 1:22.599;

11 Bourdais 1:22.615;

12 Fisichella 1:22.670;

13 Hamilton 1:22.809;

14 Kovalainen 1:22.876;

15 Massa 1:22.878;

16 Kubica 1:22:948;

17 Heidfeld 1:23.173;

18 Glock 1:23.360;

19 Trulli 1:23.623;

Not Classified: Sutil.