Briton Jenson Button topped the times for McLaren after Friday's second free practice session for this weekend's Spanish Grand Prix, the 2009 champion clocking a fastest lap time of one minute and 23.3 seconds.
Button's lap was the fastest not only of the second session, but of the day after Spaniard Fernando Alonso had clocked the quickest time of the morning's opening session in 1:24.430.
Button was a tenth off a second quickest, ahead of defending double world champion German Sebastian Vettel of Red Bull and his countryman Nico Rosberg driving for Mercedes.
Briton Lewis Hamilton, the 2008 champion and driving the second McLaren, was fourth fastest ahead of Finn Kimi Raikkonen, champion of 2007, and his Lotus team-mate Frenchman Romain Grosjean.
Australian Mark Webber was seventh-fastest in the second Red Bull ahead of seven-times champion German Michael Schumacher, 43, in the second Mercedes.
Webber also provided the most spectacular spin of the day when he flew off into the gravel at Turn Four after 55 minutes of the 90-minutes session, but managed to recover his car and continue even though it was full of stones.
On a beautiful Spring day in Catalonia, the air temperature rose to 29 degrees Celsius, but it was a poor day's work for Indian Narain Karthikeyan who barely ran in his Hispania car because of electrical problems.
After their strong showing in the morning, Ferrari slumped back into the midfield runners in the afternoon when Alonso was 14th fastest and his team-mate Brazilian Felipe Massa was 11th.
Second free practice times:
1. Jenson Button (GBR) McLaren Mercedes 1:23.399, 2. Sebastian Vettel (GER) Red Bull Racing 1:23.563, 3. Nico Rosberg (GER) Mercedes AMG 1:23.771, 4. Lewis Hamilton (GBR) McLaren Mercedes 1:23.909, 5. Kimi Raikkonen (FIN) Lotus 1:23.918, 6. Romain Grosjean (FRA) Lotus 1:23.964, 7. Mark Webber (AUS) Red Bull Racing 1:24.065, 8. Michael Schumacher (GER) Mercedes AMG 1:24.080, 9. Kamui Kobayashi (JPN) Sauber 1:24.214, 10. Nico Hulkenberg (GER) Force India 1:24.365, 11. Felipe Massa (BRA) Scuderia Ferrari 1:24.418, 12. Sergio Perez (MEX) Sauber 1:24.422, 13. Pastor Maldonado (VEN) Williams 1:24.468, 14. Fernando Alonso (ESP) Scuderia Ferrari 1:24.600, 15. Paul di Resta (GBR) Force India 1:24.688, 16. Jean-Eric Vergne (FRA) Scuderia Toro Rosso 1:24.733, 17. Daniel Ricciardo (AUS) Scuderia Toro Rosso 1:24.769, 18. Bruno Senna (BRA) Williams 1:25.047, 19. Heikki Kovalainen (FIN) Caterham 1:26.296, 20. Vitaly Petrov (RUS) Caterham 1:26.740, 21. Timo Glock (GER) Marussia 1:27.314, 22. Charles Pic (FRA) Marussia 1:27.664, 23. Pedro de la Rosa (ESP) HRT 1:28.235, 24. Narain Karthikeyan (IND) HRT