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

2:40 p.m.

Stan Wawrinka ran his U.S. Open winning streak to nine with a 7-6 (5), 4-6, 6-3, 7-5 victory over qualifier Ugo Humbert of France.

Wawrinka, the 2016 champion who missed the Grand Slam tournament last year because of two left knee surgeries, advances to face No. 25 seed Milos Raonic of Canada in the third round.

Raonic swept past Gilles Simon of France 6-3, 6-4, 6-4.

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2:20 p.m.

Defending U.S. Open champion Sloane Stephens has forced a third set in her second-round match.

The No. 3 seed lost the first set 6-4 to qualifier Anhelina Kalinina of Ukraine but battled back to take the second set 7-5.

The winner faces two-time U.S. Open finalist Victoria Azarenka.

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2:05 p.m.

No. 15 seed Stefanos Tsitsipas has been eliminated in the second round of the U.S. Open, a surprisingly early exit after his strong hard-court season.

The 20-year-old Greek was beaten by Daniil Medvedev of Russia, 6-4, 6-3, 4-6, 6-3.

Tsitsipas beat four top-10 opponents in Toronto — becoming the youngest player to do so at an event since the ATP World Tour began in 1990 — before losing to top-ranked Rafael Nadal in the final. He also reached the semifinals in Washington before a loss to No. 4 Alexander Zverev, and came into the U.S. Open as the highest-seeded debutant since Richard Gasquet was No. 13 in 2005.

But he had 64 unforced errors against just 27 winners in the match that lasted 2 hours, 48 minutes.

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12:45 p.m.

Victoria Azarenka easily reached the third round in her return to the U.S. Open, beating No. 25 seed Daria Gavrilova of Australia 6-1, 6-2.

The former top-ranked player could meet defending champion Sloane Stephens in the third round.

Azarenka, a two-time U.S. Open finalist, is playing in the tournament for the first time since 2015 after giving birth to a son.

With a ranking too low for direct entry, she received a wild card into the tournament. She is unseeded at Flushing Meadows for the first time since 2007.

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12:05 p.m.

The U.S. Open says it regrets that a player was given a code violation for changing her shirt on the court during a match, clarifying its rules on when that is allowed.

Alize Cornet of France returned from a break in action during her match Tuesday with her shirt on backward. She took off the shirt and put it back on correctly while standing near the back of the court and was given a code violation by the chair umpire.

The penalty drew criticism on social media, with people — including Andy Murray's mother, Judy — noting that men frequently change their shirts while sitting in their chairs during changeovers.

Tournament officials said in a statement Wednesday that all players can change their shirts when sitting in the player chair, adding that female players can also change their shirts in a private location near the court if it is available without being assessed a bathroom break.

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11:25 a.m.

Play at the U.S. Open is beginning under an extreme heat policy and it will remain in effect until further notice.

The women's tour has a heat rule that allows for breaks during singles matches because of the heat. The men's tour does not, but the policy was extended to the men on Tuesday when temperatures soared into the mid-90s. They are expected to remain there Wednesday.

The WTA Tour rule permits a 10-minute break between the second and third sets if either player requests it. The men's break would come between the third and fourth sets.

A statement from the U.S. Tennis Association says appropriate medical timeouts for heat-related illness also are allowed.

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11:05 a.m.

Venus and Serena Williams can set up their earliest Grand Slam meeting in 20 years if both win second-round matches at the U.S. Open on Wednesday.

Venus has an afternoon match on another hot day in Flushing Meadows against Camila Giorgi. Serena, at No. 17 seeded one spot below her older sister, should face cooler conditions during a night match against Carina Witthoeft.

If both siblings win, their third-round matchup would be their earliest at a Grand Slam tournament since they played in the second round of the 1998 Australian Open in their very first meeting on tour.

Temperatures were expected to be in the mid-90s, as high as or even a little warmer than Tuesday, when six men retired from their matches.

Defending champions Rafael Nadal and Sloane Stephens also are in action, along with past champions Juan Martin del Potro and Andy Murray — who could meet in the third round.

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