The Latest on the U.S. Open tennis tournament (all times local):

9:25 p.m.

Novak Djokovic reached his eighth U.S. Open final by beating Kei Nishikori 6-3, 6-4, 6-2.

Djokovic is bidding for his third title at Flushing Meadows and 14th Grand Slam trophy overall.

The No. 6-seeded Djokovic missed last year's tournament with an injured right elbow.

He will face Juan Martin del Potro in Sunday's final. Del Potro advanced when Rafael Nadal retired after the second set with a knee injury.

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6:30 p.m.

Juan Martin del Potro advanced to the U.S. Open final when Rafael Nadal retired after the second set with a right knee injury.

Del Potro led 7-6 (3), 6-2 when the defending champion was forced to stop playing.

He had been treated earlier and was barely moving late in the second set.

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4 p.m.

Top-seeded American Cori Gauff has been eliminated in the junior girls' singles quarterfinals.

Gauff, 14, was beaten by Dasha Lopatetskaya, a qualifier from Ukraine, 6-3, 3-6, 6-2.

Gauff won the French Open girls' title and was trying to become the first American to win two Grand Slam girls' singles titles in the same year since Jennifer Capriati in 1989. She was the youngest player to ever reach the girls' singles final at the U.S. Open last year before falling to fellow American Amanda Anisimova.

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2:30 p.m.

Tiger Woods and Serena Williams both know how to make a comeback.

Williams is set to play in her ninth U.S. Open final and 31st at all Grand Slam tournaments a year after she missed the tournament because she gave birth to her daughter, Olympia.

Woods finished sixth at the British Open, and has battled back from injuries and personal problems.

The Nike endorsers are rooting each other on about 120 miles apart — Williams at Flushing Meadows and Woods in the BMW Championship in suburban Philadelphia.

"I feel like he is on his way back," Williams said. "He's been coming back from all his back issues. It's been a disaster. But, boy, he never gave up. It's inspiring, actually. I don't think a lot of people really know how bad it was. I'm not at liberty to talk about it. But it definitely makes me realize that, OK, I can definitely do my best if he can, too."

Woods said he's been watching a lot of tennis this week and returned the tip of the cap toward Williams.

"We talk quite a bit but what she's doing is just truly remarkable," Woods said on Friday. "Having a child and having all the duties of a mother and trying to come back and trying to play at the elite level and she's doing it, back to back finals, that's pretty impressive."

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1:35 p.m.

Mike Bryan won his record-setting 18th Grand Slam doubles title and his second straight with Jack Sock, beating Lukasz Kubot and Marcelo Melo 6-3, 6-1.

Bryan won his first 16 majors with twin brother Bob, who then was sidelined with a hip injury. So Mike paired with Sock and they won Wimbledon in just their second event together.

Mike Bryan broke a tie for most major doubles titles with John Newcombe, and at 40 years, 4 months became the oldest Grand Slam doubles champion in the professional era. Six of his titles, also a record, have come at the U.S. Open.

Bryan and Sock, seeded third, are the first team to win consecutive Grand Slam doubles titles since Mike and Bob won four in a row from 2012-13. They are the first pair to win Wimbledon and the U.S. Open in the same year since Jonas Bjorkman and Todd Woodbridge in 2003.

Kubot and Melo, seeded seventh, were trying to win their second major together, having won Wimbledon in 2017.

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12:50 p.m.

Two wins from being the first men's repeat champion at the U.S. Open in a decade, Rafael Nadal meets Juan Martin del Potro in one semifinal. Novak Djokovic and Kei Nishikori play in the other matchup Friday.

All four players are past finalists at Flushing Meadows, the first time that's happened at the U.S. Open since 2011.

Nadal beat del Potro in last year's semifinals and then routed Kevin Anderson in the final for his third U.S. Open title. Not since Roger Federer won five in a row from 2004-08 has a man repeated at the final Grand Slam tournament of the season.

Federer's run was ended the next year by del Potro for the Argentine's only major title. The No. 3 seed has lost to Nadal in the semifinals in three of the last four Grand Slam tournaments.

Djokovic leads the series against Nishikori 14-2, though the Japanese did win their 2014 U.S. Open semifinal before the reigning Wimbledon champion began his run of 13 straight head-to-head victories.