Louisville Coach Rick Pitino recorded his 250th victory with the school.
The Cardinals trailed by six with 3:30 to play, but eventually took the lead for good on a jumper by Chris Smith with 2:02 remaining.
Louisville led by only one when Siva went to the line with 21 seconds left and he hit both attempts. Behanan clinched the victory with two more foul shots with 2 seconds remaining.
The Cardinals (5-0), who endured their toughest test of the season, were led by Kyle Kuric with 16 points. Behanan had 11 while Gorgui Dieng had 10 points and 16 rebounds.
D.J. Cooper scored 16 points for the Bobcats (3-1).