Stephen Holt accounted for 15 points before picking up his fifth personal foul, while Kerry Carter pitched in with 10 points for the fourth-seeded Gaels (23-11).
The fifth-seeded Runnin' Utes (21-12) were paced by Jordan Loveridge with 16 points, Brandon Taylor added 14 and Delon Wright 10 points, to go along with eight rebounds and seven assists, but he was also charged with six turnovers.
Utah opened the meeting on an 11-0 run and appeared destined to take the meeting without much effort, but even with 52.6 percent shooting from the field in the first half the team led by only seven at the break, 30-23. SMC was held to only 8-of-29 (.276) shooting through the first 20 minutes of action.
After Holt fouled out late in the second half, the Gaels ripped off a 13-0 scoring run to take their first lead of the night and eventually claim the 12- point win. Saint Mary's connected on a sizzling 65.2 percent from the floor in the period.
In addition to being outscored in the paint by a 32-14 margin, Utah was also guilty of 21 turnovers, which the Gaels converted into 22 points.
With the win, the Gaels now head to the second round of the tournament where they will take on the Minnesota Golden Gophers.