Championship leader Lewis Hamilton suffered his first retirement of the year as Sebastian Vettel romped to victory in the Singapore Grand Prix.

Vettel took his third win of the year in dominant style, controlling the race from start to finish as two safety cars led to hectic action behind.

The second caution period was caused by a man wandering along the track.

Hamilton suffered a loss of power while running fourth, dropping down the field before eventually being told to retire.

His Mercedes team-mate Nico Rosberg cut Hamilton's championship lead to 41 points by finishing fourth.

There are 150 points still available in the remaining six races, starting in Japan next weekend.

Vettel, meanwhile, is now only eight points adrift of Rosberg and a real threat for second place in the championship if Ferrari can maintain this form.

Both Mercedes were incapable of challenging at the front as Daniel Ricciardo took second for Red Bull, ahead of Ferrari's Kimi Raikkonen.

Vettel's victory was the third of the year - meeting Ferrari's pre-season target - but it was of a completely different character to those in Malaysia and Hungary.

Both of those came about because of specific circumstances - in Malaysia because Ferrari had better tyre life than Mercedes and could do one fewer stop and in Hungary because Hamilton dropped back with errors.

This time, Vettel and Ferrari were for the first time unquestionably the fastest combination on the track - in a manner reminiscent of the German's many dominant victories for Red Bull - as Mercedes, inexplicably off the pace in qualifying, continued to struggle.

Hamilton and Rosberg ran fifth and sixth in the opening stint, unable to keep up with the Ferraris and Red Bulls ahead.

Vettel, meanwhile, was in a league of his own, pulling out three seconds on the first lap and five by lap three, before backing off and stabilising his lead.

Ricciardo began to close in as the leaders neared their first pit stops, but these were triggered early when Nico Hulkenberg turned into Massa as the Brazilian rejoined after his own first stop.

Hulkenberg was penalised with a three-place grid drop at next weekend's Japanese Grand Prix for causing a collision.