Alonso beats Mercedes at opening Singapore session

SINGAPORE (AP) Mercedes driver Lewis Hamilton set the fastest time in practice for the Singapore Grand Prix on Friday, while teammate and title rival Nico Rosberg and world champion Sebastian Vettel suffered setbacks.

Hamilton's best time of 1 minute, 47.490 seconds at the Marina Bay circuit was a tenth faster than Ferrari's Fernando Alonso, who was also strong in session one when he topped the timesheets.

Rosberg's hopes of surpassing his teammate were ruined when his lap on fresh super-soft tires had to be aborted due to a red flag caused by Pastor Maldonado's heavy collision with a barrier. Rosberg was 13th fastest.

Vettel came out for only the last eight minutes of the second session after an engine failure in his Red Bull at the end of the first. The German, who has won the past three Singapore races, still had enough time to vault up to fifth on the timesheets.

However, his long absence cost him valuable long-run race preparation. While the Renault engine that failed was one that was earmarked for Friday practice sessions rather than in qualifying and the race, it did reduce the team's options to juggle its power-plants over the final races of the season. Having already used up his allowed five race engines this season, Vettel's next change will trigger a 10-place grid penalty.

His teammate Daniel Ricciardo, who is the only realistic challenger to the Mercedes pair for the drivers' championship, was third fastest, and Ferrari's Kimi Raikkonen fourth.

The competitive showing by Ferrari was a tonic after a dire performance in their home race at Monza in the previous grand prix, which precipitated the exit of long-time Ferrari company chief Luca di Montezemolo. It also indicated they were right up with Red Bull as the main threat to Mercedes this weekend.

While Ferrari was surprisingly strong, Williams would be disappointed with its lap times, with Felipe Massa and Valtteri Bottas down in 17th and 18th, as they struggled on the twisty circuit which negates their straight-line speed.