Carlos Alcaraz huffed and puffed into the Monte Carlo Masters semifinals with a 4-6 7-5 6-3 victory against local favourite Arthur Fils, who will be ruing his missed chances on Friday.
Four-time Grand Slam champion Alcaraz was made to sweat but made the most of his opponent's errors in the key moments to set up a semifinal against fellow Spaniard Alejandro Davidovich Fokina, who beat Australia's Alexei Popyrin in straight sets.
Fils made a blistering start against the world No 3, surging to a 3-0 lead with two early breaks in the opening set.
Alcaraz fought back to retrieve one break and had four chances to level in the fourth game, but Fils held firm. The Spaniard eventually drew level at 4-4, only for Fils to break once more and move ahead 5-4 in a rollercoaster set.
The Frenchman wrapped it up after saving another two break points.
He wasted seven break points, however, in the second set, and Alcaraz levelled the tie with a superb lob to steal Fils' serve in the 12th game.
Alcaraz remained inconsistent and dropped serve once again in the third game of the decider.
But experience eventually told as the 21-year-old broke back and got another break in the eighth game to the frustration of Fils, who smashed his racket on the clay.
World number 15 Fils could not regain his poise in the final game, allowing Alcaraz to finish it off routinely.
Australian Alex de Minaur wasted no time seeing off Bulgarian Grigor Dimitrov, who skidded out in a 6-0 6-0 loss after 44 minutes with a staggering 23 unforced errors.