Serena Williams was pushed to three sets on Centre Court before beating fellow American Alison Riske 6-4, 4-6, 6-3 to reach her 12th Wimbledon semifinal.
Williams broke for a 5-3 lead in the third set when Riske double-faulted on the fourth break point of the game, and then served out the win with an ace.
Williams was down a break twice in the opening set but came back both times and broke again in the final game. But in the second set, Riske broke for a 5-4 lead before holding serve to even the match.
Riske converted all five break points she created, while Williams needed 16 opportunities to break six times.
Williams is seeking an eighth Wimbledon title and 24th Grand Slam victory, while Riske was playing her first quarterfinal at a major tournament.
Simona Halep reached the Wimbledon semifinals for the second time, beating Zhang Shuai 7-6 (4), 6-1.
Halep was broken in her first service game as Zhang raced to a 3-0 lead in the first set, and the Romanian faced four more break points at 4-1. But she eventually held serve in a game that featured six deuces, and then broke back to make it 4-3. In the tiebreaker, she converted her first set point with a forehand winner.
In the second set, Halep broke twice for a 5-1 lead and converted her second match point with another forehand.
The 2018 French Open champion is looking for her second career Grand Slam title but had not reached the semifinals at the All England Club since 2014. She will next face Elina Svitolina.
Elina Svitolina came from a break down in both sets to beat Karolina Muchova 7-5, 6-4 at Wimbledon and reach her first Grand Slam semifinal.
Svitolina was down 4-1 in the opening set but broke back when Muchova served at 5-3 and won the next three games as well. In the second set, Muchova broke again for a 2-0 lead only for Svitolina to win the next five games. Svitolina failed to serve out the match on her first attempt at 5-2 but later converted her first match point when Muchova missed a backhand return.
Svitolina had lost her previous four Grand Slam quarterfinals, including at this year’s Australian Open, while her previous best result at Wimbledon was reaching the fourth round in 2017. She will next play former No. 1 Simona Halep.
Muchova was trying to become the first woman since 1999 to reach the semifinals on her Wimbledon debut.
Barbora Strycova reached her first Grand Slam semifinal by beating Johanna Konta 7-6 (5), 6-1 on Centre Court.
Strycova trailed 4-1 in the first set but broke back for 4-3 and clinched the tiebreaker when Konta netted a forehand.
The unseeded Czech player, who will face Serena Williams in the semifinals, then raced to a 3-0 lead in the second and broke again for a 5-1 lead.
Strycova’s only other Grand Slam quarterfinal appearance came in 2014 at Wimbledon, where her serve-and-volley style of play is effective on the grass courts.
Konta was the last British player remaining in the tournament. In 2017, Konta became the first British woman since Virginia Wade in 1978 to reach the Wimbledon semifinals, and she also made the last four at the French Open in June.