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Is he the Bieber daddy?

Justin Bieber took a DNA test on Friday in New Jersey to disprove Mariah Yeater's claims that he's the father of her 3-month-old son, a source confirms to Us Weekly.

According to TMZ, now it's Yeater's turn to provide a DNA sample from her son Tristyn to see whether the pop phenom's DNA matches up.

Last week, the 17-year-old's manager, Scooter Braun, told Extra that Bieber was "ready to take a paternity test, at any moment."

The announcement was a surprise, since Bieber is not obligated to take the test. Yeater, 20, had claimed that she had sex with Bieber backstage at an L.A. concert in October 2010, but she dropped her much-scrutinzed paternity suit earlier this month.

Braun explained that Bieber "doesn't mind" taking the DNA test. "He's like 'I'm just going to go ahead of it and be fine.'"

But Bieber's team is still considering legal action against Yeater, Braun hinted to Extra. "We've never even seen the lawsuit, but we're going to just get ahead of this thing and go right after it. I think it's important to hold people accountable for their actions."

Added Bieber (currently dating Selena Gomez): "We don't want it to seem like its okay for everyone to say, like, 'I had Justin's baby or [I'm] having his baby.'"