Stefanos Tsitsipas advanced to the Western & Southern Open semi-finals Wednesday evening when his opponent, Reilly Opelka, retired leading 6-5 in the first set due to a right knee injury.
The Greek star is into the last four of an ATP Masters 1000 event for the fifth time, with all of those results coming since the 2018 Rogers Cup in Toronto. Tsitsipas had never previously won a match at the Western & Southern Open, but he has now moved past a trio of tall opponents — 6’8” Kevin Anderson, 6’10” John Isner and 6’11” Opelka — at the USTA Billie Jean King National Tennis Center.
Opelka took a medical timeout at the 4-3 changeover to have his right knee taped. The American tried to battle on, saving two break points at 5-5 and holding that service game. But Opelka, a first-time Masters 1000 quarter-finalist, could not continue.
Tsitsipas will face former World No. 3 Milos Raonic or Serbian Filip Krajinovic for a spot in the final. Raonic beat the reigning Nitto ATP Finals champion in straight sets at this year’s Australian Open, but Tsitsipas owns a 2-0 ATP Head2Head series lead against Krajinovic.
The fourth seed is pursuing his first Masters 1000 title, having lost in the championship match at 2018 Canada and last year’s Mutua Madrid Open.