Bass explained that Biel, who confirmed her engagement to Timberlake in July, is a "guy's gal".
"She can get right in there and talk basketball, football, and drink a beer with you, and that's what he needs," Bass told Us Weekly. "He needs someone who can hang with the guys."
Bass, who praised Biel by saying that she "has not aged a bit", also described Timberlake as a "relationship guy".
"I think Justin was ready to marry when he was 14," he joked. "He's always been a hopeless romantic and always in love. And he's had amazing, amazing relationships and very long relationships."
Biel recently revealed that she is "cool as a cucumber" about planning her wedding to Timberlake.
New! Digital Spy breakfast show - watch Alex Fletcher discuss the day's biggest stories including the Rooneys' baby joy, Cheryl Cole's long-awaited autobiography, what's next on Doctor Who and more: