Justin and Jessica - who already have five-year-old son Silas together - were reported to have added to their family in July, and although the couple haven't addressed reports themselves, Justin's former NSYNC band mate Lance has confirmed the new arrival is ''cute''.
He said: ''The baby is cute of course, it's Justin and Jessica!''
But Lance played coy when asked for more details, including the name of the tot, as he added to 'Entertainment Tonight': ''That's a good question. Justin would kill me!''
Lance's comments come after Jessica's pal Brian McKnight revealed in early August that his friend had recently ''had a new baby''.
Reports of the tot's arrival first surfaced in July, when a friend of Jessica's mother, Kimberly Conroe Biel, claimed Kimberly had been staying with her daughter so she could witness the baby's birth.
Kimberly's friend was also reported to have said the new arrival is another baby boy.
Meanwhile, 39-year-old Justin - who married Jessica in 2012 - recently said he has ''become a mess'' since he became a father.
Asked what makes him cry, he said: ''I'm a softie, man. Watching your son learn the smallest thing can bring you to that place, for sure. I have become a mess since I became a father.''
In recent years, the 'Trolls' star has become a family man, and is now ''picky'' about the projects he takes on so that he can justify working away from his 38-year-old wife and their children.
He added: ''I always want to continue to be inspired.
''At this point in my life, I can be picky about the projects I'm going to work on.
''I choose wisely because I know it takes a lot of time to do the type of work that I want to do, whether it's making music or a film - or both in the case of 'Trolls World Tour'.
''That time takes you away from your family, so it had better be something really, really inspiring.''