Tennis star Karolina Muchova has revealed she broke down during her US Open match because she spotted her ex-boyfriend in the crowd.

Muchova, the 11th seed, has progressed to the final 16, but has been forced to overcome a number of hurdles, including a very unexpected situation in her second-round match on Friday morning (AEST).

WATCH THE VIDEO ABOVE: Muchova emotional after spotting ex-boyfriend in crowd.

Know the news with the 7NEWS app: Download today Download today

The Czech star was serving at 1-4 in the opening set when she suddenly spotted someone in the crowd that visibly affected her.

Muchova appeared to double take at 30-30 and take a moment before serving and winning the point.

But the emotions spilled over the next point with Muchova becoming visibly distraught.

She wiped away tears and apologised, which prompted the chair umpire to ask if she was OK.

Karolina Muchova broke down after spotting her ex in the crowd. Karolina Muchova broke down after spotting her ex in the crowd. Credit: StanSport

Muchova nodded and then won the point to seal the game before taking another moment to gather her composure.

Despite the unsettling situation, the 29-year-old rallied to win a gruelling battle 7-6(0), 6-7(3), 6-4.

Muchova later told Czech reporters that the sight of her ex-boyfriend scared her.

“Well it wasn’t tennis-related, so I don’t really like talking about it,” she told Czech media after her match.

“But opposite my bench, my ex-boyfriend sat down. He sometimes shows up at places where he shouldn’t be.

“That startled me a bit. I told him to leave, but he didn’t, but later he did go. It was hard to focus in that moment.”

Two days after the incident, Muchova beat compatriot and 21st seed Linda Noskova.

After that match, she was asked about the incident with her ex-boyfriend.

“Yeah, I’m alright. I didn’t make any report, and everything is good,” she said.

When asked if she felt safe by the situation, she replied: “Yeah yeah I feel OK.”

Muchova will be back in action on Tuesday morning (AEST) for her fourth-round clash against 27th seed Marta Kostyuk.

She remains one of the best players to be without a grand slam title.

Muchova has reached the final four at Flushing Meadows the past two years and was also a French Open finalist in 2023.

Meanwhile, top seed Aryna Sabalenka eased through to the quarter-finals with a 6-1, 6-4 victory over Cristina Bucsa.

American fourth seed Jessica Pegula and Czech veteran Barbora Krejcikova have also progressed to the final eight.

Emotions spill over as US Open home hero suffers historic collapse

2 min read

Shock break-up after grand slam champion’s sad exit from US Open

2 min read