Spencer Weisz added 20 points and the Tigers (7-9, 1-0) were outshot and outrebounded, but made 32 of 43 free throws.
Princeton pulled ahead 34-33 on a free throw by Peter Miller, but Penn's Tony Hicks hit a 3 at the buzzer and the Quakers led 41-36 at halftime.
Princeton gained ground on a 9-4 second-half run in which Weisz scored a layup and back-to-back 3s, then led 64-63 after Caruso's layup with 5:51 left. Penn regained the lead 71-70 on Matt Howard's layup with 3:02 left, then Princeton led 72-71 after a free throw by Caruso. The Tigers outscored the Quakers 8-3 in the final 1:01.