When Maria Sharapova's first Grand Slam match after a 15-month doping suspension ended with a victory at the US Open, she dropped to her knees and covered her face, tears welling in her eyes.

This was merely a win to get to the second round, yes, but it also clearly meant so much more to Sharapova. It meant she was back.

Displaying as much emotion on court as she ever did after one of her five major championships, Sharapova recovered after faltering midway through the match and emerged to beat No. 2-seeded Simona Halep 6-4, 4-6, 6-3 at the US Open after more than 2½ hours on Monday night.

"Behind all these Swarovski crystals and little black dresses," Sharapova told the Arthur Ashe Stadium crowd, "this girl has a lot of grit, and she's not going anywhere."

So much about Sharapova was the same as it ever was: the shot-punctuating shrieks, the aggressive baseline style, the terrific returning, the sometimes shaky serving.

Another familiar sight: She gutted out a win.

"It's been a while," said Sharapova, who missed additional time after her ban because of injuries. "It almost seemed like I had no right to win this match today. And I somehow did. I think that is what I'm most proud of."

Maria Sharapova made the most of her first Grand Slam match since returning from a 15-month doping ban, beating No. 2-seeded Simona Halep 6-4, 4-6, 6-3 in the first round of the US Open. Elsa/Getty Images

After leading by a set and 4-1 in the second, Sharapova showed some fatigue and rust, dropping five games in a row. But in the third, Sharapova regained control by going ahead 3-0, using her power to keep two-time French Open runner-up Halep under pressure.

Sharapova had not played at a Grand Slam tournament since January 2016, when she tested positive for the newly banned heart drug meldonium during the Australian Open.

The 30-year-old Russian was allowed back on the tour this April, but she was denied a wild-card invitation for the French Open the next month. The U.S. Tennis Association did grant a wild card to Sharapova, who once was ranked No. 1 but is currently 146th.

It was as if every one of Sharapova's winners on Monday -- and she compiled 60, a startling 45 more than Halep -- was her way of declaring, "Look out, everybody!"

Halep was among eight women who entered the US Open with a chance to top the WTA rankings by tournament's end. The draw at Flushing Meadows randomly paired the two players, providing a buzz-generating matchup that managed to live up to the hype on Day 1 at the year's final Grand Slam tournament.

"I gave everything I had," Halep said. "She was better."

And at an event that began without Serena Williams, who is expecting a baby, and already is missing two of its top-seven-seeded women -- No. 7 Johanna Konta, a Wimbledon semifinalist just last month, was upset by 78th-ranked Aleksandra Krunic of Serbia 4-6, 6-3, 6-4 -- Sharapova must be considered a serious title contender. She did, after all, win the US Open in 2006.

But Sharapova wasn't interested in looking too far ahead just yet.

"This is a big win for me, and I will enjoy it," she said, "then move on to the next one."

Sharapova vs. Halep was a tremendously entertaining and high-quality contest, more befitting a final than a first-rounder.

These two women have, indeed, faced off with a Grand Slam title at stake: Sharapova beat Halep in the 2014 French Open final, part of what is now her 7-0 head-to-head record in the matchup.

On Monday, they traded stinging shots, often with Sharapova -- dressed in all black, from her visor to her dress that sparkled under the lights to her socks and shoes -- aiming to end exchanges and Halep hustling into place to extend them.

"I expected her to hit everything," Halep said. "Some balls were really good. I couldn't even touch them."

Points would last 10 or 12 strokes, or more, repeatedly leaving a sellout crowd of 23,771 in Arthur Ashe Stadium clapping, yelling and high-fiving, no matter which player won them. The chair umpire repeatedly admonished spectators to hush.

Halep blinked at the end of the hourlong first set, double-faulting to face a break point, then watching Sharapova punish a 71 mph second serve with a forehand return winner. That was Sharapova's sixth return winner; she would finish with 14, more than enough to counter her seven double faults.

Halep lamented that her serve was "very bad."

Asked why, she answered: "I didn't have the timing, the feeling. I don't know why."

It was quickly 4-1 for Sharapova in the second set, and she held a break point there to allow her to go up 5-1 and serve for the victory. But she couldn't convert it. Only then did Sharapova struggle for a bit. Her footwork was off. Her forehand lost its way. She would end up losing that game and the next four, as well, as Halep managed to force a third set.

But with the outcome in the balance, Sharapova once again looked as if she had never been away, improving to 11-0 in first-round matches in New York.

Venus Williams, who moved to 19-0 in the US Open's first round with her win over Viktoria Kuzmova, is among eight women who began the tournament with a shot at the No. 1 ranking. Robert Deutsch-USA TODAY Sports

Earlier Monday, Venus Williams shook off a midmatch lapse to improve to 19-0 in the US Open's first round and stay in the hunt for the No. 1 ranking.

The No. 9-seeded Williams, at 37 the oldest woman in the field, picked up a 6-3, 3-6, 6-2 victory over Viktoria Kuzmova, a 19-year-old qualifier from Slovakia who is ranked 135th.

It was the first tour-level main-draw match of Kuzmova's career and the 967th for Williams, who won the title at Flushing Meadows in 2000 and 2001.

Williams was up a set plus a break in the second at 2-0 when she faltered. Kuzmova broke for 2-1, then pulled even at 3-all, before taking three games in a row to force a third set. But Williams righted herself there, breaking for a 2-0 lead, then digging out of a love-40 hole for 3-0.

Fifth-seeded Caroline Wozniacki rolled to a 6-1, 7-5 first-round victory over Romanian qualifier Mihaela Buzarnescu.

Wozniacki, who also has a shot at the top spot, benefited from 41 unforced errors by her 133rd-ranked opponent, including 25 in the second set.

Wozniacki, a two-time finalist at Flushing Meadows, next faces Ekaterina Makarova of Russia, who defeated German Mona Barthel 6-2, 6-1.

Two-time Wimbledon champion Petra Kvitova downed former No. 1 Jelena Jankovic 7-5, 7-5 to advance to the second round.

Kvitova, the No. 13 seed, blasted 28 winners, twice as many as her opponent, and converted nearly three-quarters of her first-serve points en route to the victory.

Wimbledon champion Garbine Muguruza advanced easily to the second round, needing just an hour to beat American Varvara Lepchenko 6-0, 6-3. The third-seeded Spaniard looked efficient in the tournament's first match on the Arthur Ashe Stadium court, firing 16 winners, twice as many as her opponent.

Other completed matches on Monday's opening day of the tournament included American Sloane Stephens ousting 2015 runner-up Roberta Vinci 7-5, 6-1; American wild card Sofia Kenin defeating 32nd-seeded American Lauren Davis 7-5, 7-5; Alize Cornet of France defeating Brit Heather Watson 6-4, 6-4; Kristyna Pliskova of the Czech Republic beating Misa Eguchi of Japan 6-2, 6-2; and American Sachia Vickery defeating Natalia Vikhlyantseva of Russia 4-6, 6-4, 6-1.

Information from The Associated Press was used in this report.