NEW YORK — After a bad-as-can-be start, dropping the first three games, Serena Williams quickly turned things around and stretched her U.S. Open winning streak to 19 matches to get back to the semifinals.
Considered the best server in women's tennis, the No. 1-seeded Williams was broken twice in a row at the outset Wednesday night before taking control for a 6-3, 6-2 victory over 11th-seeded Flavia Pennetta.
"I don't feel like I was doing too much wrong," said Williams, a five-time champion at Flushing Meadows who made her first major semifinal this year. "So I said, 'If she keeps it up, she absolutely deserves the win.' And I just tried to do a little better."
Earlier, Kei Nishikori became the first Japanese man to reach the U.S. Open semifinals in 96 years, outlasting third-seeded Stan Wawrinka 3-6, 7-5, 7-6 (7-5), 6-7 (5-7), 6-4. "I hope it's big news in Japan," said Nishikori, seeded 10th.
The match lasted 4 hours, 15 minutes. Nishikori, 24, managed to shake off any lingering exhaustion from his previous victory, which lasted 4:19 and ended at 2:26 a.m. Tuesday, equaling the latest finish in tournament history.
Nishikori began slowly against this year's Australian Open champion but eventually got his bearings and used crisp returns and strong net play to edge ahead. "Actually, I started a little bit tight, but my body was okay," Nishikori said in an on-court interview. "I don't know how I finished … but I'm very happy."
Williams is bidding to become the first woman with three consecutive U.S. Open titles since Chris Evert took four in a row from 1975-78. At 32, she also is trying to pull even with Evert and Martina Navratilova at 18 Grand Slam singles trophies.
Williams had not reached a major semifinal this year, bowing out in the fourth round at the Australian Open, the second at the French and the third at Wimbledon. The last time she didn't reach at least one major title match in a season was 2006, when she entered only two majors.
"Well, honestly, I've had a tough year in the majors, and I've (lost to) some great players that weren't in the top 10," Williams said. "So you can never underestimate anyone."
In Friday's semis Williams meets 17th-seeded Ekaterina Makarova, who defeated 2012 and 2013 runnerup Victoria Azarenka 6-4, 6-2. The other semifinal is No. 10 Caroline Wozniacki against unseeded Peng Shuai.
In the men's semifinals Saturday, Nishikori faces No. 1 Novak Djokovic or No. 8 Andy Murray, who played late Wednesday.
The last Japanese semifinalist at the U.S. Open was Ichiya Kumagae in 1918. No man from the country had made it to the final four at any major since Jiri Satoh at Wimbledon in 1933.
Nishikori, who is coached by 1989 French Open champion Michael Chang, had never eliminated top-10 opponents in consecutive matches at a major. The fourth-round marathon win against No. 5 Milos Raonic put Nishikori in his second career Grand Slam quarterfinal; he lost in that round at the 2012 Australian Open.
Things did not appear to be okay in the early going for Nishikori. Between points he would shake his arms or legs, or flex his hands. During a changeover, he placed a bag of ice on his forehead. "From outside he looks really dead," Wawrinka said, "but we know on the court he can play."