McDermott's triple erased a 64-63 deficit and boosted the Bluejays (20-4, 10-2 Big East) to a key win in the run-up to their meeting with No. 6 Villanova Sunday.
Will Artino had a double-double of 11 points and 10 rebounds.
Jahenns Manigat and Austin Chatman each added nine points for Creighton.
The Bulldogs (12-13, 2-11) got 16 points from Kellen Dunham.
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