Red Bull's Max Verstappen (24) took his eighth win in 13 races to go a massive 80 points clear of Leclerc in the standings, despite starting from 10th on the grid and suffering a 360 degree spin.
Ferrari started with Carlos Sainz (27) on the front row and Leclerc lining up third on medium tyres but ended up with neither on the podium and three pitstops dropping the latter from a potential win to sixth.
"Everything was under control and for some reason, I don't know what we did to go on the hards," Leclerc said of the second pitstop to hards -- a compound shunned by winners Red Bull and runners-up Mercedes.
The evidence warning against the hard option was already there after Alpine struggled on it.
Leclerc then had to pit again for softs.
"I said on the radio I was very comfortable on the medium and I wanted to go as long as possible with those tyres because the feeling was good. I don't know why we took a different decision," said the Ferrari driver.
"The pace on my side, I was pretty happy. The only thing is that obviously everybody will remember the last part of the race where it was a disaster for me, especially the hards. That's where I lost the race basically.
"I lost 20 seconds with the pits, another maybe six seconds on five laps on the hard because I was just all over the place with this tyre."
Ferrari boss Mattia Binotto said the hard tyres had not worked as expected "because the car wasn't working as we were expecting."
Red Bull team boss Christian Horner was asked whether Ferrari's errors were making it easy for his team.
"I can only focus on our performance," he replied diplomatically, after enquiring whether the conversation was live.
"We did a great job today. We switched our strategy on the grid," he added.
Both Red Bull drivers had been due to start on the hard tyre but decided instead to go with the soft and then switch to mediums.
"As soon as we saw Charles go onto the hard tyre, we thought OK we've really got a chance now," added Horner.
Verstappen was also asked whether he felt he had been helped by his opponents.
"We also dropped quite a few points as well from our side by having issues," he said. "I find that difficult to say that they helped me because at the end of the day you always have to perform yourself and as a team."
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