Sebastian Vettel recovered from a heart-stopping track invasion by an unidentified fan on Sunday as he convincingly won the Singapore Grand Prix and closed the gap on Mercedes.

Ferrari's Vettel led wire-to-wire for his third win this year, ahead of Red Bull's Daniel Ricciardo, with championship leader Lewis Hamilton of Mercedes forced out with mechanical problems.

But Germany's Vettel had a major shock on lap 36 when he spotted a man walking on the track, a bizarre incident which brought the race to a temporary halt.

"There's a man on the track!" he yelled over the team radio, as the safety car came out for the second time in the floodlit night race.

The disruption was the closest Vettel came to an upset and there were echoes of his quadruple world title romp with Red Bull as he calmly won by 1.4 seconds.