WASHINGTON (AP) A day before the Citi Open started, 2011 U.S. Open champion Sam Stosur spent an hour hitting on court with 173rd-ranked Jessica Pegula.
On Friday, in the hard-court tournament's quarterfinals, wild-card entry Pegula stunned the top-seeded Stosur 7-6 (4), 6-3 to get to a WTA semifinal for the first time.
Pegula said that spending time with Stosur before the tournament was a boost, because it gave a little insight to the sort of professionalism needed to reach the upper echelon of the tour.
''She probably doesn't want to hear that,'' the 22-year-old Pegula said, ''but it really helped me practicing with her.''
Stosur led 4-1 in the opening tiebreaker before losing six consecutive points to drop that set.
The only break of the match came in the next-to-last-game, when Pegula went up 5-3, then served out what she called ''probably the biggest win of my career.''
Pegula, whose parents own the NFL's Buffalo Bills and NHL's Buffalo Sabres, had lost seven of her last eight matches before arriving in Washington.
So her performance this week is ''100 percent a step in the right direction,'' Pegula said. ''I was losing to people ranked a lot lower than me. ... I was in a miserable mood.''
On Saturday, she will face Lauren Davis for a berth in the final. Davis beat Camila Giorgi 6-4, 6-4 in Friday night's last quarterfinal.
The other semifinal at the hard-court tournament will be No. 6-seeded Yulia Putintseva against No. 7 Yanina Wickmayer.
Wickmayer beat No. 4 Kristina Mladenovic 4-6, 6-3, 6-4, while Putintseva beat Risa Ozaki 6-4, 6-2.