Lewis Hamilton put his troubled Friday sessions behind him with a dominant performance in final practice in Singapore.
Sebastian Vettel took second for Red Bull, with Nico Rosberg's Williams third and Heikki Kovalainen making it two McLarens in the top four.
Hamilton, who had been unhappy with his car's performance yesterday but had to switch to a new chassis overnight to cure an electrical problem, was quickest for most of the session.
The order had been swapping frenetically in the first 25 minutes, but then the world champion hit the front with a time one second clear of everyone's best efforts at that stage. He shaved a further tenth off that pace on his next run, getting down to a 1m48.197s.
That was the best time achieved on the harder rubber, as Vettel had to use super softs to finally beat Hamilton.
The McLaren went faster still when Hamilton tried super softs a few minutes later - although his run was interrupted by a trip down the Turn 8 escape road. It took him half a minute to reverse back on course, but he then reclaimed the top spot next time around with a 1m47.632s - nearly three tenths clear of Vettel.
Rosberg and Kovalainen were 0.7s off the pace in third and fourth, ahead of the two BMWs and Rubens Barrichello, who was frustrated to encounter Renault's Romain Grosjean on his last run.
But Barrichello was happier than his Brawn team-mate Jenson Button, as the championship leader complained vehemently over the radio about his car's handling as he struggled to 14th.
The two Toyotas took eighth and 10th, sandwiching an eye-catching performance from Toro Rosso's Sebastien Buemi. The Swiss driver's team-mate Jaime Alguersuari had a delay at the start of the session when his car stalled at the pit exit and had to be pulled back to the team.
Alguersuari ended up 18th, ahead of only Grosjean and Giancarlo Fisichella - who was a long way off the pace for Ferrari.
Unlike yesterday, all 20 drivers managed to stay out of the wall in this session. Kimi Raikkonen, Tonio Liuzzi and Vettel all emulated Hamilton's escape road visit, but rejoined unscathed.
Pos Driver Car Time Laps 1. Hamilton McLaren-Mercedes (B) 1:47.632 15 2. Vettel Red Bull-Renault (B) 1:47.909 + 0.277 17 3. Rosberg Williams-Toyota (B) 1:48.332 + 0.700 18 4. Kovalainen McLaren-Mercedes (B) 1:48.420 + 0.788 14 5. Kubica BMW Sauber (B) 1:48.501 + 0.869 16 6. Heidfeld BMW Sauber (B) 1:48.526 + 0.894 13 7. Barrichello Brawn-Mercedes (B) 1:48.551 + 0.919 16 8. Glock Toyota (B) 1:48.673 + 1.041 17 9. Buemi Toro Rosso-Ferrari (B) 1:48.754 + 1.122 1710. Trulli Toyota (B) 1:48.757 + 1.125 1211. Nakajima Williams-Toyota (B) 1:48.831 + 1.199 1712. Raikkonen Ferrari (B) 1:48.864 + 1.232 1613. Webber Red Bull-Renault (B) 1:48.876 + 1.244 1514. Button Brawn-Mercedes (B) 1:48.921 + 1.289 1715. Alonso Renault (B) 1:49.032 + 1.400 1516. Liuzzi Force India-Mercedes (B) 1:49.055 + 1.423 1617. Sutil Force India-Mercedes (B) 1:49.122 + 1.490 1718. Alguersuari Toro Rosso-Ferrari (B) 1:49.399 + 1.767 1719. Grosjean Renault (B) 1:49.641 + 2.009 1620. Fisichella Ferrari (B) 1:50.039 + 2.407 21All timing unofficial