Delaware (3-4) kept the game close in the first half, using a Khalid Lewis dunk to enter halftime trailing by one, 26-25. The Blue Hens took a one-point lead, 27-26, early in the second half but Rosen hit a jumper, sparking an 18-5 run by Pennsylvania.
Rosen’s layup at the 11:46 mark capped the run and extended the Quakers lead to 45-31.
Delaware attempted to fight back but Rosen hit eight of his 12 free throws during the final two minutes of play to seal the win.
Rob Belcore paced the Quakers (5-5) on the boards, grabbing 10 rebounds to go along with his 11 points.
Jamelle Hagins led Delaware with 10 points and 11 rebounds.
Delaware committed 17 turnovers and shot just 10 of 17 from the free-throw line.