Renault's Fernando Alonso set the quickest practice time today ahead of the late-night qualifying session for Sunday's Singapore Grand Prix.
The former world champion clocked 1 minute, 44.506 seconds around the 5.067-kilometer (3.15-mile) downtown street circuit.
Alonso was more than a second faster than the best time over Friday's two 90-minute sessions, indicating teams were making progress in adapting their cars to the bumpy and tight street circuit ahead of Formula One's first ever night race.
Championship leader Lewis Hamilton of McLaren was second fastest, six-tenths of a second off Alonso's time. His title rival Felipe Massa of Ferrari was third, with Renault's Nelson Piquet Jr. fourth best.
Force India's Giancarlo Fisichella escaped unharmed after a spectacular crash after hitting the high curb on curve 10, launching his car through the air and into the concrete barriers.
Ferrari's Kimi Raikkonen locked his wheels going too quickly into a corner and went down an escape road, where his car stalled, forcing him to miss much of the session. Red Bull's David Coulthard also exited early after his car became stuck in a low gear and he was forced to return to the garage with smoke pluming from his car. He emerged only in the final four minutes of practice.
Complaints from drivers after Friday's practice forced local organizers to change the entry into pit lane. The white guideline now extends beyond the final corner to give cars an earlier indicator of a driver's intention to pit.
BMW's Nick Heidfeld said he was unhappy with the change.
"I find the pit entry even more dangerous now, because you come back exactly onto the race line and you are braking — its even worse," Heidfeld said.
There has been no rain during the practice sessions, with drivers fearing that a downpour during the race could cause glare under the lights. However, humidity and air temperature remained uncomfortably high.