Lewis Hamilton ended first practice for the Singapore Grand Prix atop the order in his Mercedes.

The Briton led the Red Bulls of Mark Webber and Sebastian Vettel in a tentative session that took a long time to get going as even backmarkers waited for track conditions to improve.

The majority of order changes at the front took place around the halfway point. In a busy few minutes, the early pace-setting Williams duo and McLaren’s Sergio Perez were usurped as the Red Bulls and Mercedes took control.

Hamilton, Nico Rosberg and Webber swapped the top spot several times before Hamilton’s 1m47.055s secured practice one honors. Webber was 0.365 second slower in second, with Vettel half a second further back but achieving his best time near the end of a long run.

Rosberg completed the top four ahead of Lotus team-mates Kimi Raikkonen and Romain Grosjean. The latter’s running was limited by a steering problem. Fernando Alonso was the fastest Ferrari in seventh.

Perez fell back to eighth, six places ahead of McLaren team-mate Jenson Button, while Felipe Massa was also outside the top 10 in the second Ferrari in 12th as Toro Rosso’s Jean-Eric Vergne and Sauber’s improving rookie Esteban Gutierrez claimed ninth and 10th, with Pastor Maldonado’s Williams 11th.

The 22 race drivers took part in the session, with no one standing aside for a reserve as teams preferred to maximize their lead racers’ track time on the tricky Marina Bay street track.

Pos Driver                Team                   Time        Gap    Laps 1. Lewis Hamilton        Mercedes               1m47.055s           20 2. Mark Webber           Red Bull-Renault       1m47.420s  +0.365s  20 3. Sebastian Vettel      Red Bull-Renault       1m47.885s  +0.830s  19 4. Nico Rosberg          Mercedes               1m48.239s  +1.184s  23 5. Kimi Raikkonen        Lotus-Renault          1m48.354s  +1.299s  18 6. Romain Grosjean       Lotus-Renault          1m48.355s  +1.300s  12 7. Fernando Alonso       Ferrari                1m48.362s  +1.307s  21 8. Sergio Perez          McLaren-Mercedes       1m49.267s  +2.212s  20 9. Jean-Eric Vergne      Toro Rosso-Ferrari     1m49.348s  +2.293s  2310. Esteban Gutierrez     Sauber-Ferrari         1m49.355s  +2.300s  2111. Pastor Maldonado      Williams-Renault       1m49.481s  +2.426s  2012. Felipe Massa          Ferrari                1m49.493s  +2.438s  1613. Valtteri Bottas       Williams-Renault       1m49.510s  +2.455s  2114. Jenson Button         McLaren-Mercedes       1m49.608s  +2.553s  2015. Paul di Resta         Force India-Mercedes   1m49.887s  +2.832s  1816. Adrian Sutil          Force India-Mercedes   1m50.092s  +3.037s  2017. Nico Hulkenberg       Sauber-Ferrari         1m50.222s  +3.167s  1718. Daniel Ricciardo      Toro Rosso-Ferrari     1m50.757s  +3.702s  1619. Jules Bianchi         Marussia-Cosworth      1m52.359s  +5.304s  1620. Max Chilton           Marussia-Cosworth      1m52.673s  +5.618s  1521. Giedo van der Garde   Caterham-Renault       1m52.920s  +5.865s  2422. Charles Pic           Caterham-Renault       1m53.647s  +6.592s  23