Justin Bieber's legal team is denying allegations that he fathered a child with a fan.
According to Radar, Maria Yeater claims she had sex with the pop sensation a year ago, and that her three-month-old baby boy is his.
A court hearing is set for December.
Radar says, "In a hand-signed affidavit, sworn under the penalty of perjury, Yeater told a California court that Bieber propositioned her on October 25 of last year, when she was 19. The pair had a sexual tryst after his concert and backstage at L.A.'s Staples Center, it's alleged in court papers."
Star's executive editor, Dylan Howard, tells CBS News, "The last line of Mariah's ... affidavit is requesting the court to compel, to force Justin Bieber to undergo a DNA test to prove, indeed, that he is the father of baby Tristan, and she's also asking for reasonable child support, effective immediately."
He adds, "The woman goes into graphic detail about the actual encounter she says she had with Justin Bieber. ... Again, these are this woman's claims and have not yet been tested by a court of law."
Bieber's representatives fired back at Yeater, telling Radar, "While we haven't yet seen the lawsuit, it's sad that someone would fabricate malicious, defamatory, and demonstrably false claims. We will vigorously pursue all available legal remedies to defend and protect Justin against these allegations."
The charges could seriously damage Bieber's squeaky-clean image -- he has openly criticized casual sex, and would have been just 16 at the time of the alleged encounter, notes CBS News' Priya David Clemens.
In March, Bieber and Disney star Selena Gomez announced they were dating. Now, that relationship could be seriously damaged, too.
While Bieber isn't the first pop star to face such accusations, he may be the youngest. Since being discovered on YouTube three years ago, he has sold millions of albums and attracted a following of very young fans.