Max Verstappen took control of the F1 drivers' championship with a comfortable win in Azerbaijan as Ferrari endured its worst day for two years.
A year after a late blowout wrecked his victory bid around this circuit, Verstappen gained redemption by chalking up his fifth win of this season and 25th of his career to open up a 21-point cushion over team-mate Sergio Perez who finished runner-up, a staggering 20.8 seconds adrift.
As Red Bull celebrated its third one-two of the campaign, rivals Ferrari, meanwhile, was left to lament a double DNF that has dropped the Scuderia 80 points adrift in the constructors' standings.
Carlos Sainz was the first to exit on lap nine, pulling off track into the run-off area at turn four with a hydraulic failure while running in fourth position.
Eleven laps later, whilst leading the race at the Baku City Circuit on strategy ahead of Verstappen and Perez, Leclerc was heading down the main straight when his power unit blew on his F1-75.
It is the Scuderia's first double DNF since the Italian Grand Prix in 2000, and it means for the second time in three races Leclerc has retired while leading after a turbo failure brought a premature end to his Spanish Grand Prix in May.
It also means Leclerc has now failed to convert four consecutive pole positions into a race victory, the first time that has happened to a driver since Juan Pablo Montoya in 2002.
Leclerc has also now dropped to third in the drivers' title race, 34 points adrift of reigning champion Verstappen who was 46 behind after the first three races.
Once the five red lights disappeared, Leclerc was marginally slower off the line compared to Perez, and that made all the difference.
On the short run into the 90-degree turn-one left-hander, Perez managed to take the inside line as Leclerc also locked up his front-left.
It was the crucial move at the front of the pack as the field filed through the opening corners without incident.
It was not until lap nine, following a static race up until that point, that the complexion of the event changed with Sainz the first to retire.
It sparked a virtual safety car period, leading to Ferrari taking a gamble with Leclerc by bringing him in and switching from the medium-compound tyres to a set of hards in a bid for either a long one-stop or a two-stop.
Leclerc's stop, however, was a slow 5.7s due to the front jack not being released in time
Mercedes opted for the same strategy with Russell and Hamilton, but for the latter, it was yet another VSC/safety car period that failed to work out for the seven-time F1 champion.
Hamilton, though, gained a place when Vettel locked up on lap 13 into turn three after making a clean pass on Alpine's Esteban Ocon but there will have been frustration for the Briton given the earlier VSC that went against him.
Verstappen takes lead as Leclerc exits
Two laps later, and even though Perez had appeared to be quicker throughout the weekend, the Mexican had no answer for Verstappen as the Dutch driver made an easy pass towards the end of the long straight.
Perez had also been instructed over the team radio that there should be "no fighting" with Verstappen, and the former offered no resistance.
That led to Perez making a stop at the end of lap 16, albeit a slow one at 5.7s as he was held despite there being no apparent issue.
When Verstappen pitted after 18 laps, that propelled Leclerc into the lead but for two laps only as the Monégasque then suffered his PU failure.
Magnussen retired on track, leading to a second VSC after 33 laps and free stops for the top three in Verstappen, Perez and Russell.
Running in fourth place, AlphaTauri's Pierre Gasly stayed out, as did team-mate Yuki Tsunoda, pushing Hamilton down to sixth but with the Briton having complained four laps earlier of his back 'killing him' due to the violent porpoising of his W13.
Hamilton made short work of Tsunoda, however, on lap 35, leaving him free to chase down Gasly, completing his task on the Frenchman 10 laps later.
Gasly had to settle for fifth ahead of Vettel, Alpine's Fernando Alonso, Ricciardo and Norris, with Ocon completing the top 10.
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