Sloane Stephens defeats Victoria Azarenka for third consecutive time

Reporting from new york —  Sloane Stephens had modest goals the first few times she played against Victoria Azarenka, a two-time Grand Slam winner. “I was just happy to be on the court with her and competing and pushing her and playing good points and things like that. Not necessarily expecting to win,” Stephens said. “Now I’m in a position where I fully believe I can win the match and I go out there ready to execute and ready to play.”

Stephens, the defending U.S. Open champion and No. 3 seed, overcame some wobbles in her third-round match against Azarenka on Friday and beat her for the third straight time. In a match that featured some terrific rallies, Stephens won the last three games after action was halted to close the roof at Arthur Ashe Stadium and clinched a 6-3, 6-4 decision. “It was a few points in the second that really kind of changed the match,” said Stephens, who broke back after Azarenka had broken her serve for a 4-3 lead.

Stephens advanced to face No. 15 Elise Mertens, who defeated Barbora Strykova 6-3, 7-6 (4). Mertens defeated a fatigued Stephens a few weeks at Cincinnati but Stephens said her legs feel good. “She’s a good player, so anything can happen,” Stephens said.

Men’s updates

Rafael Nadal, the defending men’s champion and No. 1 seed, won a 39-shot rally to capture a third-set tiebreaker and fuel a 5-7, 7-5, 7-6 (7), 7-6 (3) comeback over rising star Karen Kha-chanov of Russia at Arthur Ashe Stadium.

Nadal improved his match record this year to 43-3, but Khachanov — despite committing three double faults in the third-set tiebreaker—made Nadal work hard for 4 hours and 23 minutes. “These kind of matches make you feel confident, make you feel stronger,” Nadal said. “At some point you need to go through some tough moments.”

Nadal will face Nikoloz Basilashvili of Georgia, who ousted Guido Pella in four sets.

A few minutes before Nadal won, 2017 U.S. Open runnerup Kevin Anderson finished a comeback in a 4-6, 6-3, 6-4, 4-6, 6-4 victory over 19-year-old Canadian Denis Shapovalov. Anderson’s big serve topped out at 136 mph as he fired 11 aces and put 71% of his first serves in play. The new roof at Louis Armstrong Stadium was activated for the first time during the second set.

Anderson, 32, said his experience was an asset. “But I had to definitely use all of it to get through today. He definitely didn’t make it very easy for me out there,” said Anderson. Next up for Anderson, seeded No. 5, is No. 9 Dominic Thiem, who got past Taylor Fritz of Rancho Palos Verdes 3-6, 6-3, 7-6 (5), 6-4. “Going to have my work cut out for me,” Anderson said.

Umpire cautioned

Chair umpire Mohamed Lahyani “went beyond protocol” when he left his chair to have an animated chat with Nick Kyrgios during Kyrgios’ match against Pierre-Hugues Herbert on Thursday, but Lahyani was allowed to continue officiating matches here, U.S. Open officials said. Lahyani was “advised to adhere to proper protocols in all matches that he officiates moving forward,” according to a statement issued Friday.

Etc.

The top-seeded American, No. 11 John Isner, advanced with a 7-6 (8), 6-7 (6), 6-3, 7-5 victory over unseeded Dusan Lajovic. Isner will face Canada’s Milos Raonic, who eliminated 2016 champion Stan Wawrinka 7-6 (6), 6-4, 6-3…. Attendance at the Billie Jean King National Tennis Center was a single-day record of 70,162.

helene.elliott@latimes.com

Follow Helene Elliott on Twitter @helenenothelen