Leclerc, who is from Monaco, will look to clinch his second pole position of the season in qualifying later Saturday. In third practice, he was 0.053 seconds ahead of Valtteri Bottas and 0.213 clear of Formula One championship leader Lewis Hamilton. Red Bull's Max Verstappen was fourth fastest.
Leclerc has impressed at times in his first season with Ferrari, but Vettel is struggling with his composure once again. Despite enjoying idyllic racing conditions under blue skies and a dry track, Vettel appeared to lock the inside left wheel and went straight into the exit barriers at Saint Devote. The four-time F1 champion swore on team radio, then clambered out of his car and walked back to the team garage with his race helmet on.
Race stewards moved quickly to remove the car from the track. It had damage to the front left tire but this did not appear serious enough to rule Vettel out of qualifying later Saturday. Vettel has not won any of the past 13 races , dating back to last year's Belgian GP in late August. His vulnerability under pressure was evident the last two seasons, when he made key mistakes in losing the title race to Hamilton.
Leclerc had a near miss with the Haas car of Kevin Magnussen moments after Vettel's crash. "Magnussen is crazy, we nearly crashed," Leclerc barked on team radio. Ferrari is clearly feeling the pressure with Mercedes finishing 1-2 in all five races this season. Hamilton is chasing his sixth F1 title and leads the championship by seven points from Bottas heading into Sunday's race.
Special tributes to three-time F1 champion Niki Lauda will be held shortly before Sunday's race. He died on Monday less than one year after undergoing a lung transplant.
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