Ferrari's Sebastian Vettel overcame the shock of coming across a track intruder mid-race and won the Singapore Grand Prix on Sunday, while runaway championship leader Lewis Hamilton suffered his first retirement of the season, injecting new life into the fight for the Formula One title.
Vettel led from start to finish in a race that was temporarily interrupted by a fan wandering on the track, which prompted the second of two safety-car periods that tactically helped the German notch his third win of the season, by 1.4 seconds over Red Bull driver Daniel Ricciardo.
Ferrari's Kimi Raikkonen was third, as the top three finished in the positions they started at the Marina Bay street circuit.
"I was able to look after my tyres and control the pace," said Vettel, whose 42nd career win moved him into outright third on the all-time list. "Overall a perfect weekend, I am very, very happy."
Hamilton suffered an engine-clamp failure that took away boost power, and after several laps of touring around attempting a reset, he retired on lap 33 of 61.
His championship lead over Mercedes teammate Nico Rosberg, who finished fourth, was trimmed from 53 to 41 points - 252 vs. 211 - with Vettel a further eight points back on 203. There are six races left.
The first safety-car period came on lap 13 following a collision between Williams' Felipe Massa, who was coming out of the pits, and Force India's Nico Hulkenberg. Race stewards blamed Hulkenberg, and he will get a three-place grid penalty at the next race.
The second came in bizarre circumstances when a fan was seen wandering on the track near the Anderson Bridge section. Vettel, who was the first to see him, shouted over the team radio "there is a man on the track!" and the safety car was immediately deployed. The casually dressed man soon climbed over a trackside barrier and off the track and the race resumed.
Vettel joked after the race that he hoped the fan at least got a decent photo.
While this race was likely to be only a temporary aberration to Hamilton's otherwise dominant season, Vettel was not giving up hope of challenging for the championship.
"If we have more weekends like this, yes," Vettel said. "All we have to do is look after ourselves, maximum attack. We still have a small chance. Maybe we can make the impossible possible. We will definitely go for it."
The German made a storming start to the race, leading by three seconds after a brilliant opening lap and extending that to 5.3 seconds after five laps. Ricciardo had whittled that back to 3.6 seconds after 12 laps and the Australian driver looked likely to close onto the back of his former Red Bull teammate, but then the first safety car emerged.
After that caution period, Vettel adopted a different strategy, driving conservatively as the field closed up behind him. He then suddenly burst away to put a two-second gap on Ricciardo in the space of one lap. Again, Ricciardo began to erode the margin, only for another safety car period to negate Red Bull's expected superior speed late in the stint.
"Both safety cars came out at crucial times, but nonetheless his pace was good," Ricciardo said, while quipping that he was so frustrated by the intruding fan ruining his tactical plan that "I was tempted to swerve and clip him."
Hamilton was racing in fourth place when suddenly the car began to lose power.
"I was feeling super optimistic," Hamilton said. "I was on the prime tyres and the three cars in front were on the options but I was easily keeping up with them and thinking 'we have a race on our hands'. They were telling me to change all these things and then I was overtaken by two Manors so I knew l was last. When they started to pull away, I knew it was over."
Williams driver Valterri Bottas finished fifth, Red Bull's Daniil Kvyat sixth and Force India's Sergio Perez seventh.
Toro Rosso teenager Max Verstappen finished eighth, refusing team orders in the closing laps to move over for teammate Carlos Sainz Jr. who was ninth. The team believed Sainz had a better shot of overtaking Perez, because he was on fresher tyres, but team principal Franz Tost later acknowledged Sainz stood little chance, and Verstappen was right not to move over.
Sauber's Felipe Nasr passed Romain Grosjean on the penultimate lap for the last points position.