Sloane Stephens reached her first Grand Slam semifinal since 2013 by beating 16th-seeded Anastasija Sevastova 6-3, 3-6, 7-6 (4) at the U.S. Open.
The 83rd-ranked Stephens has won 13 of her past 15 matches. She was one of four American women in the quarterfinals at Flushing Meadows, the most since five made it that far 15 years ago.
Sevastova beat Maria Sharapova in the fourth round and was trying to reach the first major semifinal of her career. She received treatment from a trainer late in the first set Tuesday for a problem with her upper right leg.
Stephens went 11 months between tournaments because of surgery on her left foot in January, returning to competition at Wimbledon in July.
Her ranking was 934th before she reached consecutive semifinals at hard-court tournaments in Toronto and Cincinnati in August.
Her only previous trip to the final four at a major tournament came at the Australian Open four years ago.