Dee Davis hit the first of two free throws with :34 left to tie the game at 65-65, but missed a go-ahead free throw that could have decided the game in regulation.
Matt Stainbrook and Davis each converted a pair of free throws in overtime, but Davis' 3 with 1:26 left was the Musketeers' lone field goal of the extra period. Xavier was just 1 for 6 from the field in the final two minutes.
Creighton (11-13 2-9 Big East) closed it out by going 6 for 6 from the line in the final :16.
Groselle finished with 15 points for the Bluejays, who shot 45.8 percent from the field (27 of 59).
Jalen Reynolds led Xavier with 17 points as the Musketeers (14-9, 5-6) were just 22 of 57 from the field.