Tsitsipas held his nerve in two tie-break sets and won 84 per cent of first-serve points (38/45) to advance after one hour and 42 minutes. The 22-year-old improves to 15-5 this year following his second victory in four ATP Head2Head contests against Isner.
Tsitsipas is bidding to reach his third straight final on the ATP Tour. In his two most recent events prior to the ATP Tour suspension, the World No. 6 lifted the Open 13 Provence trophy and finished as runner-up at the Dubai Duty Free Tennis Championships for the second straight year.
Following his win against 6’10” Isner, Tsitsipas will meet another big-serving American, 6’11” Reilly Opelka, in the quarter-finals. Opelka landed 19 aces and dropped just two points behind his first serve (33/35) to eliminate sixth seed Matteo Berrettini 6-3, 7-6(4).
After 11 service games without a break point, Tsitsipas was unable to convert set point at 5-6, 30/40, in the first set. But the reigning Nitto ATP Finals champion moved up the court behind his forehand and served well to clinch the opener with a dominant tie-break performance. The Greek converted his second set point with an ace down the T, his fourth ace of the match.
Another tie-break was needed in the second set and Tsitsipas made the crucial breakthrough at 4/4. The five-time ATP Tour titlist forced Isner into his backhand corner with depth to extract an error and earned two match points with a powerful forehand up the line. Tsitsipas needed only one opportunity, directing the ball back into Isner’s backhand corner to force another mistake from his opponent.