Britain's Jenson Button, of McLaren, was quickest on a wet second morning of the final pre-season testing of the winter in Barcelona on Friday.
Button, the 2009 world champion, was 0.216 seconds quicker than Germany's Adrian Sutil, driving for Force India in conditions that started off very wet before beginning to dry up.
Sutil's impressive performance came a day after he was confirmed as the Force India team's second driver for 2013 after a 12-month absence.
His compatriot Niko Huelkenberg, in a Sauber, was third, while world champion Sebastian Vettel was tenth in his Red Bull, for whom Mark Webber had set the quickest pace on Thursday.
1. Jenson Button (GBR/McLaren-Mercedes) 1:25.936 (33 laps), 2. Adrian Sutil (GER/Force India-Mercedes) 1:26.152 (42), 3. Nico Huelkenberg (GER/Sauber-Ferrari) 1:27.246 (36), 4. Nico Rosberg (GER/Mercedes) 1:27.672 (50), 5. Romain Grosjean (FRA/Lotus-Renault) 1:27.757 (52), 6. Fernando Alonso (ESP/Ferrari) 1:27.878 (52), 7. Pastor Maldonado (VEN/Williams-Renault) 1:29.132 (35), 8. Daniel Ricciardo (AUS/Toro Rosso-Ferrari) 1:29.682 (40), 9. Max Chilton (GBR/Marussia-Cosworth) 1:29.772 (39), 10. Sebastian Vettel (GER/Red Bull-Renault) 1:31.159 (26), 11. Giedo van der Garde (NED/Caterham-Renault) 1:39.036 (29)