Lewis Hamilton was handed a dramatic victory in Bahrain after a cruel engine problem denied Ferrari's Charles Leclerc a maiden win.
Leclerc, in just his second race for Ferrari, was on course to become the third-youngest winner in Formula One history following a commanding drive.
But with just nine laps to run, Hamilton took advantage of the Ferrari's lack of speed to sail past the young Monegasque and take an unlikely win, the first of his championship defence.
Bahrain Grand Prix podium
1st - Lewis Hamilton
2nd - Valtteri Bottas
3rd - Charles Leclerc
Valtteri Bottas was also the fortunate recipient of Leclerc's demise to steal second place, and secure an improbable one-two for Mercedes.
The Finn, who won in Melbourne a fortnight ago, retains his lead in the championship by one point. Leclerc took the chequered flag in third as the race ended under a safety car after Daniel Ricciardo's Renault engine failed.
Sebastian Vettel finished only fifth after he dramatically spun while duelling for second with Hamilton. It marked yet another error for the German after a series of mistakes blighted his title challenge last year.
British teenager Lando Norris crossed the line an impressive sixth for McLaren and his first Formula One points.
On Saturday, Leclerc came up with the goods to deliver a huge statement of intent by blowing away Vettel to become the sport's second youngest pole-sitter, and 24 hours later carried on his fine form.
His start was poor and he fell to third, but after passing Bottas and then Vettel was back in charge just five laps later.
Leclerc was signed by Ferrari as an emerging talent, with Vettel's number one status set to go unchallenged. Indeed, the paddock murmurings before today's race centred on whether Ferrari would afford Vettel preferential treatment.
Leclerc took the took the decision out of his team's hands before the late engine problem struck.
"What's happening," he yelled as it emerged Leclerc had lost significant straight-line speed. There were heads in hands in the Ferrari garage as it became apparent the problem was terminal.
Hamilton had been nine seconds behind, but within just three laps he was all over the back of the Ferrari gearbox before biding his time to make his move and seal the 74th win of his career.
"You have to take it as it comes," added Hamilton who went over to offer his commiserations to Leclerc.
"This is a great result for the team, but this guy here [Leclerc] has got wins in him. Congratulations to him."
Leclerc said: "It happens and it is part of motorsport. Unfortunately today was not our day.
"I am extremely disappointed. We have been lucky because the safety car came out at the end, but it is hard to take. I am sure we will come back stronger."
Earlier in a chaotic race, with Leclerc in control of the lead, Hamilton and Vettel duelled at high speed for second position on lap 38. Hamilton made the move stick around the outside of the right-handed turn four before Vettel lost control of his Ferrari and spun.
To make matters worse, his front wing dramatically broke free from his car. He fell to ninth for repairs before recovering to fifth, but this will be a weekend to forget for the four-time world champion.