Romanian seventh seed Simona Halep suffered a shock first-round defeat at the US Open as she lost to Ukrainian qualifier Daria Snigur in three sets.

Having led the third set 5-1, the 20-year-old held her nerve to beat two-time major winner Halep 6-2 0-6 6-4.

It is a first Tour-level match win for the world number 124, in her first meeting with a top-10 ranked player.

Snigur could barely believe her achievement as Halep sent a backhand into the net to confirm a huge opening day upset at Flushing Meadows, New York.

Halep, who reached the Wimbledon semi-finals in July, lost just six points as she claimed a one-sided second set to level the match.

But, unfazed, a double break of serve in the third put Snigur on the verge of victory before she withstood a late fightback from her opponent and converted her third match point.

It was not long before tears of joy followed as she came back from 0-30 behind in the final game, while her father watched on in disbelief, resting his hands on his head, as his daughter spoke to the crowd.

“I’m very happy. It’s impossible for me,” said Snigur. “I have to say thanks to Simona for this incredible match. I want to thank all the fans who watched our match today.

“Of course this match is for Ukraine, for my family, for everyone who supported me. I want to say thank you to you all.”

She will face Poland’s Magdalena Frech or Canadian Rebecca Marino in round two.

Andreescu beats Tan after dress change

Canada’s 2019 champion Bianca Andreescu prevailed in three sets against Harmony Tan after being forced into a last-minute outfit change.

The 22-year-old asked to leave the court during the warm-up because of an issue with her dress.

“It’s not my fault, it’s Nike’s fault, this dress is so bad,” she told the umpire.

She initially dominated on her return, wrapping up a 26-minute opening set without losing a game.

Tan, who reached the last 16 at Wimbledon, established a 4-0 lead on her way to forcing a decider, but the momentum swung firmly in Andreescu’s direction once more as she dominated the third to win 6-0 3-6 6-1.

Andreescu, who reached the fourth round in her other US Open appearance in 2021, has a win rate of 92% at the major – but she will face a tough task next against Brazil’s Beatriz Haddad Maia.

Haddad Maia, seeded 15th, produced a devastating display, which included 17 winners, as she thrashed Croat Ana Konjuh 6-0 6-0 in one hour.

Elsewhere, Greek third seed Maria Sakkari and Tunisian fifth seed Ons Jabeur both progressed.

Sakkari overcame Germany’s Wimbledon semi-finalist Tatjana Maria in three sets, winning 6-4 3-6 6-0 against an opponent who had beaten her in the third round at SW19.

Jabeur, who reached her first major final at the All England Club, earned a 7-5 6-2 win over American Madison Brengle.

American 18-year-old Coco Gauff also progressed with a straight-set victory over France’s Leolia Jeanjean.

A couple of breaks of serve in either set saw the 12th seed start her campaign with a comfortable 6-2 6-3 win on Arthur Ashe Stadium.