Jenson Button put his recent disappointments behind him to set the pace in final practice for the European Grand Prix.
In a session dominated by traffic and unexpected mistakes from several frontrunners, Button clocked a 1:38.562 to lead the way ahead of Romain Grosjean.
The Lotus driver was 0.098s adrift of the McLaren while his team-mate Kimi Raikkonen was third quickest.
Grosjean, the only driver to set a lap time in the opening 15 minutes, clocked a 1:40.136 to get proceedings underway. Raikkonen slotted into second place ahead of Lewis Hamilton, who admitted after Friday's running that McLaren got the balance wrong in FP2.
Raikkonen was the next to lead the way, the first driver into the 1:39s. The Finn, though, soon lost out to Hamilton who in turn lost out to Pastor Maldonado, the driver who set the pace on Friday morning.
Halfway through the session it was Maldonado ahead of Hamilton, Raikkonen, Sebastian Vettel, Nico Rosberg, Button, Grosjean and Felipe Massa.
Moments later Vettel became the P1 holder as the reigning World Champion took 1:39.448 to lap the 25-corner Valencia circuit. The German was three-tenths up on Maldonado. With 25 minutes remaining Fernando Alonso - the last driver to set a lap time - finally made his mark, taking seventh place.
Shortly after drivers began to swap to the softer - and quicker - Pirelli tyres. Grosjean was the first to do so, posting a 1:38.655 to take the P1 slot by almost a second. Meanwhile, Pedro de la Rosa had the first notable incident of the session as he put his HRT into a massive slide which ended with a spin. No damage, though.
As others switched to the soft tyres, Button took the P1 slot with a 1:38.562. The Brit, though, was alone in challenging Grosjean for the position as others fell short, often due to traffic or, like with Vettel, due to an error on his flying lap.
01 Jenson Button McLaren 1:38.562 17 laps
02 Romain Grosjean Lotus 1:38.655 0.093 18 laps
03 Kimi Raikkonen Lotus 1:38.759 0.197 18 laps
04 Nico Hulkenberg Force India 1:38.819 0.257 17 laps
05 Paul di Resta Force India 1:38.892 0.330 17 laps
06 Sergio Perez Sauber 1:39.084 0.522 20 laps
07 Michael Schumacher Mercedes 1:39.141 0.579 15 laps
08 Lewis Hamilton McLaren 1:39.178 0.616 17 laps
09 Felipe Massa Ferrari 1:39.318 0.756 15 laps
10 Pastor Maldonado Williams 1:39.357 0.795 18 laps
11 Kamui Kobayashi Sauber 1:39.358 0.796 19 laps
12 Fernando Alonso Ferrari 1:39.395 0.833 15 laps
13 Sebastian Vettel Red Bull 1:39.434 0.872 12 laps
14 Bruno Senna Williams 1:39.543 0.981 13 laps
15 Nico Rosberg Mercedes 1:39.946 1.384 20 laps
16 Jean-Eric Vergne Toro Rosso 1:40.037 1.475 17 laps
17 Daniel Ricciardo Toro Rosso 1:40.134 1.572 20 laps
18 Heikki Kovalainen Caterham 1:40.681 2.119 15 laps
19 Mark Webber Red Bull 1:41.282 2.720 4 laps
20 Vitaly Petrov Caterham 1:41.931 3.369 15 laps
21 Pedro de la Rosa HRT 1:42.758 4.196 14 laps
22 Charles Pic Marussia 1:42.815 4.253 16 laps
23 Narain Karthikeyan HRT 1:42.943 4.381 14 laps
24 Timo Glock Marussia 1:43.124 4.562 16 laps