Lewis Hamilton produced a sublime drive in wet conditions to extend his championship lead over Sebastian Vettel to 28 points, the widest margin of the season so far.
Vettel started on pole but suffered serious damage to the rear of his car before the first bend when he was struck by Ferrari teammate Kimi Raikkonen, who tried to squeeze past Verstappen in a wild start.
The stunning crash then took out Fernando Alonso, whose car was briefly airborne as all drivers struggled in the conditions early in the race.
With Vettel, Verstappen and Raikkonen wiped out and the track drying a few laps in, Hamilton seized his opportunity and held off the stubborn Daniel RIcciardo - but this was no procession to the finish line.
Only 12 cars completed a race which saw the safety car called out on multiple occasions. Hamilton was struggling to build a commanding lead over Ricciardo in the first half of the race, with the Red Bull driver dutifully chipping away at the Briton's lead until Hamilton changed to the ultra-soft tyre midway through the race.
Hamilton was able to build a commanding lead of over 10 seconds, only for that to be wiped out on lap 38 when Ericsson crashed, giving Ricciardo another shot at a frustrated Hamilton.
But Hamilton admirably kept his composure under pressure, and guided his Mercedes home for a second successive victory in what could be a huge result in his quest for a third title in four years.
As it happened:
Chequered flag - LEWIS HAMILTON WINS THE SINGAPORE GRAND PRIX
Hamilton crosses the line a few seconds before the two-hour limit is hit, so he has complete one more lap. He comes through it safely to win in Singapore, and what a drive it was. There's some way to go in the season, but a title-winning drive, you could say.
03:27 to go
Hamilton is closing this out with what has been a wonderful drive. Despite everything the weather has thrown at him and the multiple safety cars, the Briton has always looked in control.
06:12 to go
Sainz is holding off Perez for fourth. If he can hang on, that’ll be his best ever finish.
09:34 to go
Kevin Magnussen is out, so we’ve now got 12 drivers left in the race.
12:56 to go
Hairy moment for Hamilton, who tells his team: "Something's flapping on my front tyre." But it looks like it was some paper debris that's now gone
14.38 to go
Hamilton leads by 2.773 and proves that he was right to ignore the instructions. It really has been a masterful display of driving from him at times.
18:23 to go
Hamilton ignoring orders. He was told to take his foot off the gas to back the field up into Ricciardo and not give anyone a free stop if the safety car comes back out, but Hamilton didn’t like it, said it wasn’t “comfortable”, so it back to putting it in.
20:21 to go
It's become clear that we won't complete 20 more laps so we're counting down rather than up now. Twenty minutes and 21 seconds to go and it's a slow middle sector from Hamilton. The gap is suddenly down to 1.7 seconds.
The safety car is coming in. Ricciardo has another shot at catching Hamilton, but the clock is ticking - only a maximum of 25 minutes of racing remaining. And now Ricciardo has Bottas hot on heels, of course.
Max Verstappen is talking about the crash at the start. He says he got away better than Vettel, who he thinks didn’t see Raikkonen. "I couldn’t get out of that sandwich."
Lewis Hamilton isn't happy...
"Why another safety car?" he asks. "I can't believe we had that gap and now..."
He's reassured that his "pace was very good before this safety car".
Ericcsonloses the rear of his Sauber and crashes into the barrier! You know what means? Yep, the safety car...
Ricciardo chipping away but struggling to make serious inroads into Hamilton's lead. This time the Australian takes just 0.024 seconds off the leader.
Ricciardo isn't settling for second as he responds with the fastest lap of the race himself, but it's only 0.2 seconds faster than Hamilton, who remains in complete control in Singapore.
But what a response from Hamilton! The Mercedes driver is a second quicker than Ricciardo and easily sets the fastest of the race so far. He's 9.3s ahead.
New fastest lap for Ricciardo, who is faster in sectors one and three, with Hamilton more rapid in sector two. Over the whole lap, Ricciardo is 0.2s quicker.
Little to choose between Hamilton and Ricciardo for sheer pace at the moment, but Hamilton has a nice cushion.
Hamilton rejoins on ultra-softs. The gap between Hamilton and Ricciardo is briefly up to 11.5 seconds with those pitstops done, but Ricciardo immediately takes a big bite out of the lead, chomping it down to 8.8 seconds.
Hamilton about to come in...
In fact, Ricciardo opts for ultra-softs and rejoins still second.
"These tyres are starting to go in the rear," Ricciardo says. Red Bull is concerned he'll come back in traffic if he pits now. Meanwhile, Hamilton extends his lead to 10 seconds. Ricciardo might as well just pit and gamble on the slicks...
Hamilton now leads by over 7 seconds...
Impressive driving from Hamilton at the moment. His car is not faster than Ricciardo's at the moment and his tyres seem to be holding him back - yet he's just extended his lead at the front. Hamilton does a new fastest lap and gets the gap up to 6 seconds - but he'll have to pit at some point.
For the first time since the restart, Ricciardo puts in a better lap than Hamilton. That gets the lead down to just over 4 seconds, but the Australian still has plenty of work to do.
"Tyres are still good. This track's drying very slowly," reports Hamilton, who has extended his lead over Ricciardo to 4.6 seconds.
Bottas is back in third and still unable to challenge Ricciardo. Mercedes reassures Bottas his first-sector pace is picking up, but he's losing ground of over one second per lap.
Hamilton increasingly comfortable. Another fastest lap and the Briton leads by 2.8 seconds.
The safety car is in and we're racing again on a drying track. "Nine tenths faster last lap," Mercedes informs Hamilton, who is widening the gap over Riccardo at every sector.
"Has everyone changed tyres except me?" asks Hamilton. "Not sure that's a good idea, everyone's had a free stop."
Kvyat crashes and the safety car is back out. Ricciardo has swapped to the intermediates and returns in thrd, just behind Hulkenberg.
First signs that Hamilton may not just be leading a procession. Ricciardo chipping away has his lead and has cut it down by almost a second. The full wet tyres are working better than the intermediates, whch is what Hamilton is on.
Alonso has dropped to 17th now. He reports "no power" and is heading to the pits to retire. Not surprising really given that he was briefly airborne after being hit by Raikkonen in that big crash at the start.
Ricciardo matched Hamilton briefly, but the lead gap has now grown to 4.3 seconds.
The safety car makes way and the race resumes. Hamilton leads, and that's not a position he expected to be in. Can the master in the wet bring home another victory for Mercedes?
"This race is going to be about getting the car home in one piece," Mercedes tells Hamilton. "I realise that," he replies.
That really was one of the most exciting starts to an F1 race that you're ever likely to see. Vettel out, Verstappen out, Raikkonen out. Vettel wasn't taken out by the initial crash involving Verstappen and Raikkonen but replays suggest split fluid from his own car may have caused him to spin and end up going backwards down the track.
Lap 1/61 GO! GO! GO!
Unbelievable start as Raikkonen collides with Verstappen immediately and also takes out Vettel! Hamilton will lead from Ricciardo when the safety car makes way. Wow.
We're just about ready to go in Singapore. Just a reminder that Vettel is on pole, with championship leader Lewis Hamilton back on the third row of the grid in fifth.
We've never actually seen the Marina Bay street circuit tested in the wet before, so this race could throw up a few surprises.
We're 15 minutes away from the start of the Singapore Grand Prix, which of course has the added spectacle of being a night race. But the main talking point is the extremely wet conditions. the rain has been pounding the track for several hours and we can expect some thrills and spills.