NEW YORK -- Sloane Stephens doesn't betray much emotion on the court, so all of the double fist pumps at the conclusion of her US Open match against former No. 1 Victoria Azarenka made perfectly clear just how tight and tense things had been.
Stephens, the defending champion and No. 3 seed, grabbed the last three games after returning from a brief break while the Arthur Ashe Stadium's roof was shut Friday and pulled out a 6-3, 6-4 victory over two-time runner-up Azarenka to reach the fourth round.
What helped Stephens after the 8-minute delay?
"Just kind of refocusing," she said.
Stephens went from up a set and a break at 3-1 in the second to down 4-3 when Azarenka took three games in a row. With light rain falling, play was halted while the cover was closed -- although play carried on everywhere else, including the new Louis Armstrong Stadium, the only other arena at Flushing Meadows with a retractable roof.
"The man upstairs was looking out for me," Stephens said. "Unlucky for her."
When they resumed, she took control.
"I mean, of course it was a change of momentum. I won't be sitting here finding excuses; it's just what happens. You just have to accept (it)," said Azarenka, a former No. 1 who won the Australian Open twice and lost to Serena Williams in the US Open final twice. "I just think from the tournament side, if they (are) expecting the showers, I think it might be better to just close the roof right from the beginning. I think it would just be smarter."
This was a match filled with lengthy exchanges and some fantastic shotmaking by both women.
Stephens was just a bit better, particularly on the most crucial points. She won half of Azarenka's 10 service games. And Stephens also made 10 fewer unforced errors, 27-17.
This is Stephens' sixth Grand Slam tournament since she had foot surgery in January 2017, and the other five followed a boom-or-bust pattern: In two, she reached the final, including at the French Open in June; in the other three, she exited in the first round.
It was Azarenka's first US Open in three years. In addition to being a two-time runner-up, Azarenka won the girls' singles title in 2005. She falls to 0-3 against Stephens this year, and 0-6 all-time.
This time, the American will seek a quarterfinal spot when she faces No. 15 Elise Mertens of Belgium on Sunday.
Mertens, who beat Stephens at a recent hard-court tuneup tournament, reached the fourth round in New York for the first time by defeating No. 23 Barbora Strycova 6-3, 7-6 (4). The other fourth-round matchup in that quarter will be No. 7 Elina Svitolina against No. 19 Anastasija Sevastova.
Information from the Associated Press was used in this report.