US Open: Frances Tiafoe reaches the semifinals when Grigor ...

NEW YORK (AP) — Frances Tiafoe reached the U.S. Open semifinals for the second time in three years when his quarterfinal opponent, Grigor Dimitrov, stopped playing because of an injury in the fourth set Tuesday night.

Tiafoe was leading 6-3, 7-6 (5), 6-3, 4-1 when Dimitrov retired from the match.

Dimitrov had played a five-setter in the fourth round and appeared to be fading late in the third set against Tiafoe, grabbing at his left hamstring and walking gingerly between points. After that set, Dimitrov was visited by a trainer and then headed to the locker room for treatment.

He returned to the court for the start of the fourth set but wasn’t able to move properly and eventually quit.