Billionaire Mark Cuban says one of Donald Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE’s family members rolled her eyes at the GOP nominee during the first presidential debate.

“There was a point when [Trump] said something, and this family member just rolled their eyes, and she saw I had seen it,” he said at the Advertising Week New York conference in New York City Thursday, according to Page Six.

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Cuban, who supports Democratic nominee Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE, refused to identify the Trump relative.

“[I] don’t want to bust them,” he said.

Cuban also noted that Clinton and her family stayed to mingle with supporters after the contest, while the Trumps quickly departed.

“[It was] exit stage left immediately,” the owner of the NBA’s Dallas Mavericks said.

Cuban last week said he had accepted an invitation from Clinton’s campaign to watch her “overwhelm” Trump from a front-row seat.

Trump countered by threatening to invite Gennifer Flowers, who had an extramarital affair with Clinton’s husband, former President Bill Clinton William (Bill) Jefferson ClintonGOP brushes back charges of hypocrisy in Supreme Court fight Battle lines drawn on precedent in Supreme Court fight Sunday shows - Ruth Bader Ginsburg's death dominates MORE. Flowers did not attend the debate.

Cuban ultimately clarified he did not have a front-row seat.

Hillary Clinton on Thursday, though, said Cuban’s presence at the debate still rattled Trump.

“At the debate the other night, one of my well-known supporters, Mark Cuban, was there in the front row, and he really, I think, unsettled my opponent,” she said at a rally in Des Moines, Iowa.

Polls released after Monday’s debate show Clinton with a modest bump both nationally and in swing states.

Clinton leads Trump by about 3 percent nationally, according to the latest RealClearPolitics average of polls.