Mariah Yeater - a self-confessed fan of the star - claims baby-faced Bieber fathered her son during a back-stage quickie after one of his concerts.
Yeater says that blonde four-month-old Tristyn Anthony Markhouse Yeater's looks like his 'dad' and has the same mouth!
The Sun reports that Yeater alleged: "Look, just look at his mouth. Look familiar?" adding:
"I pray that Justin sees these photos, looks at Tristyn and knows in his heart that this is his child and our child. It's going to be a nightmare for all of us if he keeps denying it. I just want what is right for our son, I feel terribly hurt that we have been abandoned and none of my calls to Justin were returned."
Justin meanwhile is said to be taking a paternity test later this month but denies he is Tristyn's father, while Yeater may be charged with statutory rape as Bieber was under-age at the time of their tryst.
Justin Bieber. Backstage quickies. Babies. Paternity tests. Blimey. It's just not right, is it?
Check out the pics - what do you reckon?