The third round of the U.S. Open was a star-studded affair.

Pop star Justin Bieber and wife Hailey were sitting in the crowd Friday rooting for Coco Gauff. The 19-year-old American tennis star dropped her opening set against Belgium’s Elise Mertens. But Gauff regrouped and won the match.

Gauff credited Bieber for inspiring her comeback victory, advancing to the fourth round of the tournament. 

"I definitely saw who was there," Gauff said in reference to seeing Bieber on the big screen during her match. "I thought, ‘I cannot lose in front of Justin Bieber.’ I didn’t lose a game after I saw that."

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Coco Gauff celebrates a victory

Coco Gauff of the U.S. celebrates her victory over Elise Mertens of Belgium in the third round of the U.S. Open at the USTA Billie Jean King National Tennis Center Sept. 1, 2023, in New York City. (Frey/TPN/Getty Images)

Bieber, a two-time Grammy Award winner, sat in the stands at the Billie Jean King National Tennis Center wearing a polka-dot hat, pink sunglasses and a leather jacket.

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Miami Heat star Jimmy Butler, a friend of Gauff, was also on hand for the third round.

Earlier in the week, the Obama family attended the U.S. Open, but Gauff said Bieber's presence left her "star-struck."

"I got a little tight when I first saw him, then I remembered President (Barack) Obama and Michelle Obama were at my first-round match," the sixth seed added, according to Reuters.

"I was definitely star-struck with Justin. ‘Never Say Never’ was … one of my favorite songs when I was a kid. Then, ‘Baby, Oh, Baby.’ I could go through all his songs. Then Hailey, too, coming. I guess it was a little date night for them, which was really cool."

Justin and Hailey Bieber watch Coco Gauffs match

Justin and Hailey Bieber watch Coco Gauff of the United States play against Elise Mertens of Belgium in the third round of the U.S. Open at the USTA Billie Jean King National Tennis Center Sept. 1, 2023, in New York City. (Frey/TPN/Getty Images)

There has been no shortage of celebrities in the building during Gauff's matches at this year's tournament. Fashion designer Anna Wintour and retired U.S. Olympic skier Lindsey Vonn watched Gauff's first-round match.

Gauff also revealed which music superstar she hopes will soon watch her play.

"If (Beyoncé) ever came — oh my goodness, I hope they would not show her on the screen. Maybe at the end," she said via the Women's Tennis Association.

Justin Bieber attends day five of the US Open

Justin Bieber attends day five of the 2023 U.S. Open at Arthur Ashe Stadium at the USTA Billie Jean King National Tennis Center Sept. 1, 2023, in New York City. (Jean Catuffe/GC Images)

Gauff also mentioned that Beyoncé’s ongoing Renaissance World Tour was on her mind during Friday's come-from-behind win.

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Gauff will next take on former world No.1 Caroline Wozniacki in the fourth round.