INDIAN WELLS, Calif. -- Defending champion Simona Halep and No. 3 seed Stan Wawrinka exited, and No. 4 Rafael Nadal and No. 5 Kei Nishikori barely survived on a day of high drama in the BNP Paribas Open..
Halep, seeded fifth, fell to top seed and two-time champion Serena Williams 6-4, 6-3 in Wednesday night's featured match in 16,100-seat Stadium 1. They were scheduled to meet in last year's semifinals, but Williams withdrew minutes beforehand with a knee injury.
Williams' older sister Venus had done the same before they were to meet in the 2001 semifinals. Fans unleashed a torrent of boos, some allegedly made racial comments, and both players boycotted the tournament for the next 14 years.
Just as Venus had in 2001, Serena won Miami two weeks after Indian Wells last year.
Venus returned to the BNP Paribas Open this year as the 10th seed but lost to qualifier Kurumi Nara of Japan in the second round after receiving a bye.
After last year's withdrawal, Serena said: "It feels really good to get that win (against Halep). She obviously has been in good form the past couple years."
Still, Williams improved to 7-1 against Halep.
"She played really well today," said Halep, who pronounced herself healthy after she had encountered a series of physical problems this year. "I have to get better to be closer to her."
Wawrinka, a two-time Grand Slam singles champion, lost to 15th-seeded David Goffin of Belgium 6-3, 5-7, 7-6 (5). Wawrinka nearly pulled off an amazing comeback after trailing 6-3, 4-0 and then 5-2 in the third set.
Wawrinka led 4-2 in the tiebreaker, but Goffin won the next three points. At 5-5, Wawrinka sailed a putaway overhead at the net way long. On the next point, he netted a forehand off a running cross-court forehand by Goffin to end the match after 2 hours, 25 minutes in 90-degree heat.
"Well, not too great a day, not too great a level," lamented Wawrinka, who applauded the crowd and signed a couple of autographs on his way out of 8,000-seat Stadium 2. "I didn't have the rhythm yet. Was a match without a brain, let's put it that way."
The fourth-ranked Wawrinka had not lost a set to the 5-foot-11 (1.80-meter), 150-pound (68-kilogram) Goffin in their three previous matches, although they had played four tiebreakers (all won by Wawrinka).
Goffin, who saved two match points in his second-round victory over 18-year-old wild card Frances Tiafoe of the United States, reached his second ATP Masters 1000 quarterfinal and first on hardcourts. He also advanced to the Rome quarters on clay last year.
Goffin, ranked 18th, had been 1-25 against top-10 players
with a 14-match losing streak against them. He beat then-No. 9 Milos Raonic in the
Basel quarterfinals in 2014.
Both Nadal and Nishikori saved match points in their victories.
Nadal, who has won three singles and two doubles titles at Indian Wells, held off 18-year-old Alexander Zverev 6-7 (8), 6-0, 7-5 in 2 hours, 34 minutes in Stadium 1.
Nadal trailed 5-2 in the third set against the 6-foot-6 (1.98-meter) German, whom the Spanish star has touted as a future No. 1. Zverev netted a putaway forehand volley while serving at 5-3, 40-30.
"I missed probably the easiest shot I had the whole match," Zverev moaned.
Showing his inexperience, Zverev fell apart after that, dropping 14 of the next 15 points for the match. Nadal, though, displayed his trademark tenacity.
"Is a great victory," crowed Nadal, who has slumped since winning the 2014 French Open for his 14th Grand Slam singles title (tied for second all-time with Pete Sampras behind Roger Federer's 17). "I'm very happy about it. I am especially happy about the mentality on court, the spirit of fight during the whole match, believing that I can win a match during the whole time even in the tougher situations."
Nishikori, 5-foot-10 (1.78-meters), withstood 23 aces by 6-foot-10 (2.08-meter) John Isner to prevail 1-6, 7-6 (2), 7-6 (5). Nishikori, who escaped a match point at 5-6 in the third set, reached the Indian Wells quarterfinals for the first time in eight appearances.
Isner upset world No. 1 Novak Djokovic to reach the 2012 final, in which he lost to Federer. The Swiss star missed this year's tournament while recovering from arthroscopic knee surgery.
Djokovic, who has won the last two Indian Wells titles and four overall, and Nadal are the only remaining past men's champions. Both are in the top half of the draw. The top-seeded Djokovic will meet No. 7 Jo-Wilfried Tsonga, and Nadal will face Nishikori.
The bottom half will produce a first-time Indian Wells finalist. No. 10 Marin Cilic will play Goffin, and No. 8 Gael Monfils will take on No. 12 Raonic.
Serena Williams will play third-seeded Agnieszka Radwanska, the runner-up to Flavia Pennetta in 2014, in one semifinal. Radwanska will rise one notch to No. 2, tying her career high, after beating eighth-seeded Petra Kvitova 6-2, 7-6 (3) on Wednesday.
The other semifinal will be determined today. No. 13 seed Victoria Azarenka, the 2012 champion, will meet unseeded Magdalena Rybarikova of Slovakia, and No. 18 Karolina Pliskova of the Czech Republic will face unseeded 18-year-old Daria Kasatkina.
In the men's doubles quarterfinals, No. 8 seeds Edouard Roger-Vasselin of France and Nenad Zimonjic of Serbia edged No. 3 Bob Bryan and Mike Bryan 4-6, 6-1 [14-12]. The Bryans, who starred at Stanford in the late 1990s, won the Indian Wells title in 2013 and 2014.
Roger-Vasselin is the baby of the group at 32. Zimonjic will turn 40 in June, and the Bryans will be 38 next month.