NEW YORK -- No one, not even Maria Sharapova herself, knew quite what to expect from her return to Grand Slam tennis at the US Open.
It had been 19 months since she had entered a major tournament. She played only nine times anywhere since a 15-month doping suspension ended in April. Two three-set tussles into her stay at Flushing Meadows, it's clear that Sharapova's game might be patchy, but she is as capable as ever of coming up with big strokes in big moments -- and maybe, just maybe, could stick around for a while in a depleted draw.
Sharapova became the first woman into the third round at the US Open by using 12 aces to help set aside a poor start and come back to beat Timea Babos of Hungary 6-7 (4), 6-4, 6-1 on Wednesday in Arthur Ashe Stadium.
"Look, I certainly have expectations, just because I know I've been in these stages before and I've been able to execute. There's a certain level of 'I know I can do this. I've done it before.' I want to have that feeling again," Sharapova said. "But there's also the realistic understanding of 'OK, you haven't been in this situation for a while. It's going to take a little time.' Of course, managing expectations is part of it, learning as you play the matches, which is something I haven't done for a long time."
Her victory was an early highlight on a busy day that featured 87 singles matches on the schedule after rain washed out most play a day earlier.
The biggest upset in the women's draw on Wednesday came from Ekaterina Makarova a 6-2, 6-7, 6-1 winner over fifth-seeded Caroline Wozniacki.
Wozniacki had won all seven previous matches she had played against Makarova, whose best Grand Slam showing was a semifinal run at Flushing Meadows in 2014. Wozniacki is a former No. 1 who reached the US Open final in 2009 and '14. Her departure means four of the top seven women are out of the field just three days into the two-week tournament.
American Sloane Stephens registered a big upset of her own, knocking off 2014 Australian Open runner-up Dominika Cibulkova 6-2, 5-7, 6-3 to reach the third round.
Stephens, 24, is ranked only 83rd after going 11 months without entering a tournament because of an injured left foot that required surgery. She returned to the tour at Wimbledon in July.
Stephens and the 11th-seeded Cibulkova each made the same number of unforced errors, 39. The difference in the match was the winner count: Stephens had 43, nearly double Cibulkova's 22.
Not too long ago, Stephens appeared to be a rising star in tennis, making at least the fourth round at six consecutive Grand Slam tournaments, including a semifinal run at the 2013 Australian Open. If she can beat Ashleigh Barty next, Stephens would get to the fourth round at a major for the first time in nearly 2½ years.
While Stephens and Makarova provided the drama, past US Open champions Venus Williams and Svetlana Kuznetsova also advanced. Williams reached the third round behind a 7-5, 6-4 win over France's Oceane Dodin. Kuznetsova's entry to the second round required a bit more work, as she staved off three match points to defeat Marketa Vondrousova 4-6, 6-4, 7-6 (2).
Wednesday wasn't easy for Sharapova, either.
She made 19 unforced errors in the first set, which ended with her missing twice on forehands to give the 59th-ranked Babos the lead. But as the match went on, Sharapova looked more and more like someone who used to be ranked No. 1 and owns five major titles -- including the 2006 US Open -- than someone who needed a wild-card invitation from the United States Tennis Association because she is now ranked 146th on account of her ban and lack of play.
Sharapova last participated in a major tournament at the 2016 Australian Open, where she tested positive for the newly banned heart drug meldonium. She declined to answer a reporter's question about how frequently she has been drug tested this year.
Babos said she thought it was "a little bit unfair for the other players" that Sharapova was let into the field, a sentiment echoed by No. 20 seed CoCo Vandeweghe, who would have preferred that a fellow American get that wild card.
But Sharapova is here, and she does not appear ready to be an easy out.
"Towards the end of the second set, I felt like I was the fresher player. Going into a third set, that's a good position or a good feeling to have," said the 30-year-old Russian, who wore a strip of black tape on the left forearm that bothered her earlier in the month.
She also had a sleeve on her right elbow to keep that arm warm, she said.
Sharapova cut down her miscues to 12 unforced errors in the second set, then just five in the third, and finished with a 39-13 advantage in winners, looking as strong as she did while eliminating No. 2 seed Simona Halep in a three-set thriller at Ashe on Monday.
"I definitely wanted to enjoy the quality of tennis that I played with the other night," Sharapova said, "but I also wanted to put my mind onto this one."
She already has spent nearly five hours on court, and so perhaps the yelling and fist-pumping she showed at the end against Babos were as much a reflection of a sense of relief as celebration.
If 14 return winners were a key to getting past Halep, it was Sharapova's serving that really made a difference down the stretch against Babos: She won 16 of the last 19 points she served.
"In key moments, she showed why, no matter what happened to her, why she is a big player and good player," Babos said, "because she came up with some very, very good shots and she didn't miss her opportunities."
No. 19 Anastasia Pavlyuchenkova missed her opportunities Wednesday, as she fell 3-6, 6-3, 6-2 to Christina McHale of the U.S. In other matches, No. 10 seed Agnieszka Radwanska of Poland beat Petra Martic 6-4, 7-6 (3), and Vandeweghe beat fellow American Alison Riske 2-6, 6-3, 6-4.
The Associated Press contributed to this report.