PARIS — John Isner won a hard-fought all-American contest against Jack Sock 7-6 (6), 4-6, 6-4 after throwing a big tantrum in the Paris Masters quarterfinals on Friday.
Isner looked set for a straight-sets win when he served a break up at 4-3 in the second set but lost his cool after a foot-fault call.
Isner, who had not dropped his serve once since the start of the week, was unsettled by the decision. He shouted at umpire Damien Dumusois, hit a double fault, and was broken twice in a row, allowing Sock back in the match.
But the change in momentum did not last long. Isner, who hit 17 aces, capitalized on Sock’s mistakes to break him twice early in the decider.
The 27th-ranked Isner equaled his best result at the indoor tournament, making it to the last four for the first time in five years in the French capital. Isner will play in the semifinals of a Masters 1000 tournament for the first time since April 2015.
Given the pace of the court in Paris, there were only a few baseline rallies and most of the points ended very quickly.
Isner, the fastest server on the tour, was put under pressure by Sock, his occasional doubles partner, in the first-set tiebreaker. Sock earned a set point with a superb backhand lob down the line, but that was the final point he scored in the set: Isner hit an ace, followed that up with a serve and volley winner, and Sock hit a forehand wide.
Isner broke for 2-1 in the second with a low passing shot, but suddenly lost his grip on the match after the umpire’s call unsettled him.
Sock, who made it to the fourth round at the U.S. Open, struggled with his serve at the start of the decider, and could not come back despite a late surge from 4-0 down.