Lewis Hamilton was quickest for McLaren in a truncated opening practice session for the Singapore Grand Prix.
Issues with the kerbing on the exit of Turns 3 and 14 developed during support race session, and led to an half-hour delay while the kerbs were removed before the session could get underway.
With only a two-hour gap between Friday practice sessions in Singapore, practice one was reduced to just 60 minutes to keep the timetable on schedule, although a further problem with the kerbing - this time at Turn 7 - brought the red flags out eight minutes from the end. Quick work by marshals saw the offending kerb section removed within five minutes so a little more running could take place.
When the session had initially got underway, Ferrari's Felipe Massa was the early pacesetter, sitting atop the times with a 1m52.043s lap for a long while.
It was only as twilight became darkness in the final 20 minutes that things began to hot up at the front. McLaren had completed little running in the first half of the session, but Jenson Button deposed Massa with a 1m50.952s when he did get going.
That was comfortably beaten by a 1m50.082s from Sebastian Vettel's Red Bull two minutes later, with the championship leader finding another 0.4s next time around.
Lewis Hamilton then appeared up front with 12 minutes to go, edging a tenth ahead of Vettel. The German soon fought back and delivered a lap half a second quicker than the McLaren's - but Hamilton had more speed to come as well, putting in a 1m48.599s to reclaim the top spot by 0.406s.
The second kerb problem prevented any further changes at the front, with most of the field braving the traffic jam at the pit exit but only a handful of drivers improving in the three minutes of running that followed the green light.
Vettel retained second, with team-mate Mark Webber third.
Aero work early in the session meant Fernando Alonso only had a few flying laps in his Ferrari. He took fourth, ahead of Button and Massa.
A strong session for Force India saw Adrian Sutil and Paul di Resta seventh and ninth, split by Michael Schumacher's Mercedes, with Nico Rosberg 10th in the sister silver car.
In his first appearance since Nurburgring practice in July, Narain Karthikeyan led HRT team-mate Daniel Ricciardo until the final moments, when he was pipped to 23rd. The Indian was given Tonio Liuzzi's car for this session as a warm-up for his racing return at his inaugural home grand prix next month.
In addition to the kerb issues, there was another a brief red flag interruption at the session's halfway point when Heikki Kovalainen's Lotus came to a halt with its front brakes on fire. Unlike last year, when the Finn famously had to put out a blaze on his Lotus himself in the race, Kovalainen was able to summon marshals to extinguish the fires, though he still assisted with pushing the car off the circuit.
The session's other main incident was a collision between Webber and Timo Glock. Contact was made as the Red Bull tried to pass the Virgin into the penultimate corner, smashing a chunk from Webber's front wing and leaving Glock with a puncture.
Pos Driver Team Time Laps 1. Lewis Hamilton McLaren-Mercedes 1m48.599s + 10
2. Sebastian Vettel Red Bull-Renault 1m49.005s + 0.406 15
3. Mark Webber Red Bull-Renault 1m50.066s + 1.467 16
4. Fernando Alonso Ferrari 1m50.596s + 1.997 11
5. Jenson Button McLaren-Mercedes 1m50.952s + 2.353 12
6. Felipe Massa Ferrari 1m52.043s + 3.444 14
7. Adrian Sutil Force India-Mercedes 1m52.251s + 3.652 13
8. Michael Schumacher Mercedes 1m52.416s + 3.817 12
9. Paul di Resta Force India-Mercedes 1m52.435s + 3.836 13
10. Nico Rosberg Mercedes 1m52.815s + 4.216 13
11. Rubens Barrichello Williams-Cosworth 1m52.991s + 4.392 17
12. Jaime Alguersuari Toro Rosso-Ferrari 1m53.050s + 4.451 17
13. Pastor Maldonado Williams-Cosworth 1m53.399s + 4.800 18
14. Sergio Perez Sauber-Ferrari 1m53.703s + 5.104 19
15. Kamui Kobayashi Sauber-Ferrari 1m53.749s + 5.150 12
16. Bruno Senna Renault 1m53.765s + 5.166 17
17. Sebastien Buemi Toro Rosso-Ferrari 1m53.785s + 5.186 16
18. Vitaly Petrov Renault 1m54.736s + 6.137 8
19. Jarno Trulli Lotus-Renault 1m54.821s + 6.222 9
20. Heikki Kovalainen Lotus-Renault 1m56.198s + 7.599 8
21. Jerome D'Ambrosio Virgin-Cosworth 1m57.798s + 9.199 13
22. Timo Glock Virgin-Cosworth 1m58.792s + 10.193 6
23. Daniel Ricciardo HRT-Cosworth 1m59.169s + 10.570 17
24. Narain Karthikeyan HRT-Cosworth 1m59.214s + 10.615 18
All Timing Unofficial
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