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

6:55 p.m.

Pablo Carreno Busta was unable to duplicate his U.S. Open run from a year ago, forced to retire from his second-round match because of left thigh pain.

Carreno Busta reached the semifinals last year in Flushing Meadows.

Joao Sousa of Portugal led Carreno Busta 4-6, 6-3, 5-7, 6-2, 2-0 when the No. 12 seed from Spain had to stop playing.

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5:45 p.m.

The U.S. Open and the Grand Slam Board will review chair umpire Mohamed Lahyani's interaction with Nick Kyrgios during a second-round match.

Tournament referee Brian Earley says Lahyani took the unusual step of climbing out of his chair to speak with Kyrgios "to make sure he could communicate effectively" because of noise in the arena. Earley says Kyrgios was told by Lahyani that the chair umpire "would need to take action" if Kyrgios' "seeming lack of interest in the match continued."

According to Early, Lahyani "was concerned that Kyrgios might need medical attention."

U.S. Tennis Association spokesman Chris Widmaier says that Early and the tournament's chief umpire, Soeren Frienel, are still reviewing the episode.

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5:15 p.m.

Make it 18 for 18 for Roger Federer in the second round of the U.S. Open.

The No. 2 seed beat Benoit Paire 7-5, 6-4, 6-4 to continue his streak of reaching the third round in the tournament he has won five times.

Federer will next face No. 30 seed Nick Kyrgios.

Federer is 7-0 against Paire, winning 16 of 17 sets against the Frenchman.

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4:55 p.m.

Madison Keys cruised into the third round of the U.S. Open, beating fellow American Bernarda Pera 6-4, 6-1.

The U.S. Open runner-up last year served eight aces and never lost her serve in the match that lasted 1 hour, 12 minutes.

The No. 14 seed will play either Aleksandra Krunic or Kirsten Flipkens in the next round.

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4:10 p.m.

No. 14 seed Fabio Fognini of Italy was upset in the U.S. Open's second round by 55th-ranked John Millman of Australia 6-1, 4-6, 6-4, 6-1.

By reaching the third round, Millman equaled his best showing at any Grand Slam tournament.

Fognini, the husband of 2015 U.S. Open champion Flavia Pennetta, was kicked out of the U.S. Open doubles tournament last year after vulgarly insulting a female chair umpire during a first-round loss in singles.

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3:40 p.m.

After an unusual visit from the chair umpire, Nick Kyrgios turned around his match and won it to reach the U.S. Open's third round.

Kyrgios was down a set and 3-0 in the second when official Mohamed Lahyani climbed down from his seat and went over to speak to the player — something rarely, if ever, seen during a professional tennis match. At one point, Lahyani said, "I want to help you."

The No. 30-seeded Kyrgios, who once was suspended by the ATP men's tour after not trying during a match, started playing better and eventually beat Pierre-Hugues Herbert of France 4-6, 7-6 (6), 6-3, 6-0.

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3:10 p.m.

Alexander Zverev has finally reached the third round of the U.S. Open.

The No. 4 seed beat Nicolas Mahut 6-4, 6-4, 6-2 for his best result in the year's final Grand Slam tournament.

Zverev had been knocked out in the second round in his three previous appearances.

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2:50 p.m.

Three-time major champion Angelique Kerber got through a second-round test at the U.S. Open, edging 82nd-ranked Johanna Larsson of Sweden 6-2, 5-7, 6-4.

Kerber moved ahead in a third set filled with lengthy baseline exchanges by breaking in the next-to-last game when Larsson double-faulted.

The No. 4-seeded Kerber won the U.S. Open in 2016. Her other Grand Slam trophies came at that year's Australian Open and this year's Wimbledon.

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1:45 p.m.

The Williams sisters will lead off the night session at Arthur Ashe Stadium on Friday with their third-round showdown at the U.S. Open.

It will be the 30th tour-level meeting between Venus and Serena, but the earliest at a Grand Slam since Venus won a second-round matchup at the 1998 Australian Open. That was the first time they played each other as pros.

Venus is the No. 16 seed, one spot above her younger sister. They have twice met in the U.S. Open final, trading victories in 2001 and 2002.

They will be followed on Ashe by 2009 champion Juan Martin del Potro against Spain's Fernando Verdasco.

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1:25 p.m.

The Belarussians are coming.

Aliaksandra Sasnovich and Aryna Sabalenka have won second-round matches at the U.S. Open, continuing Belarus' top performance in a major.

With former No. 1 Victoria Azarenka and Vera Lapko also winning their first matches at Flushing Meadows, Belarus had four players reach the second round of a Grand Slam for the first time.

Azarenka had already reached the third round and was joined by the 33rd-ranked Sasnovich, who upset No. 11 seed Daria Kasatkina 6-2, 7-6 (3), and No. 26 seed Sabalenka, who ousted Vera Zvonareva 6-3, 7-6 (7).

Azarenka faces defending champion Sloane Stephens in the third round Friday. Lapko was eliminated by 15th-seeded Elise Mertens on Wednesday.

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11:50 a.m.

The extreme heat policy is in effect for the third straight day at the U.S. Open.

A 10-minute break will be allowed between the second and third sets of women's singles matches if either player requests one. For men's singles matches, the break would come between the third and fourth sets.

U.S. Open officials began the policy, which is a rule on the women's tour but not the men's, on Tuesday, when temperatures first soared into the mid-90s. It was 86 degrees (30 Celsius) just before Thursday's day session on Arthur Ashe Stadium was to begin.

The Open says the policy will remain until further notice.

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11:45 a.m.

The first two rounds of the U.S. Open have always been a breeze for Roger Federer.

Alexander Zverev is still trying to master them.

Federer tries to remain unbeaten in the first two rounds at Flushing Meadows, and Zverev finally tries to make the third round for the first time when both are in action Thursday.

Former champions Novak Djokovic and Maric Cilic also have second-round matches on the men's side, and 2016 champ Angelique Kerber is among the women in action.

Federer, 17-0 in second-round matches, faces Frenchman Benoit Paire. The No. 2 Federer has won all six meetings, though Paire had two match points in their last matchup in June in Germany before the five-time U.S. Open champion won 9-7 in a third-set tiebreaker.

Zverev, the No. 4 seed, is in the U.S. Open for the fourth time. He faces another Frenchman, Nicolas Mahut.

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