NEW YORK -- Ukrainian Daria Snigur's first career win on the WTA Tour was a big one. American Coco Gauff's first career win at Arthur Ashe Stadium was an easy one.
The 20-year-old Snigur stunned No. 7 seed Simona Halep 6-2, 0-6, 6-4 in the first round of the US Open, then struggled through tears to explain what the victory meant to her family and her country during its war with Russia.
"No comment, I think, because it's impossible for me now,'' Snigur said.
Snigur wore a pin in the colors of Ukraine's flag on her chest and put her hands around it after the final point.
Meanwhile, No. 12-ranked Gauff cruised past Leolia Jeanjean 6-2, 6-3. Gauff had lost each of her previous three appearances on Arthur Ashe, including doubles.
Snigur was making her first appearance in the main draw of a Grand Slam after emerging through the qualifying rounds last week.
On Wednesday, she joined tennis superstars such as Rafael Nadal, Coco Gauff, John McEnroe, Iga Swiatek and 2021 U.S. Open runner-up Leylah Fernandez in the "Tennis Plays for Peace Exhibition,'' an event organized by the U.S. Tennis Association that raised $1.2 million.
It took place in Louis Armstrong Stadium, which may have calmed Snigur's nerves when she was sent back out there Monday.
"I think it helped me because I was here in 'Tennis Plays for Peace' and I think it helped me a little bit,'' Snigur said during an on-court interview.
Snigur won the Wimbledon girls singles title in 2019, but failed in her first eight attempts to qualify for the main draw of a Grand Slam before finally breaking through. She was 0-2 on tour and was facing a top-20 opponent for the first time.
And in Halep, it was one of the hottest players in women's tennis. The two-time Grand Slam champion had won 19 of her previous 22 matches and recently returned to the top 10.
But Snigur responded nicely after Halep won the second set, racing to a 5-1 lead in the third. Halep fought off a couple match points while taking the next three games before Snigur finally closed it out when Halep sailed a backhand long.
Snigur then dropped her racket and covered her face as she fought back tears.
Elina Svitolina's run to the 2019 semifinals is the best performance by a Ukrainian in the U.S. Open. One of five of them in this year's draw, Snigur will face Canadian Rebecca Marino on Wednesday. First, she was going to savor a stunner.
"I want to say thanks to all the fans who watched our match today,'' she said.
Elsewhere, Harriet Dart produced a fine performance against 10th-seeded Daria Kasatkina to win 7-6 (10-8),1-6, 6-3 -- the Briton's first main-draw victory and first against a top 10-ranked opponent.
There were 10 breaks of serve in a back-and-forth first set which Dart eventually won via tiebreak after saving two set points, before Kasatkina made light work of the second set.
Dart, 26, then found herself 3-1 down in the deciding set but rallied back to beat Kasatkina in two hours and 30 minutes.
"I'm a little bit in shock right now," Dart said. "Physically I don't feel great but I really tried to stick at it and push through. I can't believe I got the win.
"What's so exciting about women's tennis is anyone can win."
Third-seeded Maria Sakkari and No. 17 Caroline Garcia were among the other early winners on the women's side, with Sakkari overcoming Wimbledon semifinalist Tatjana Maria in three sets.
Bianca Andreescu, the 2019 U.S. Open champion, needed three sets to get past Harmony Tan, the French player who beat Williams in the first round at Wimbledon.
The Associated Press contributed to this story.