The Chanticleers (23-9) will meet fifth-seeded Winthrop on Sunday in a repeat of last year's title-game matchup won by Coastal Carolina.
Leading by three with 24 seconds left, the Chanticleers' Warren Gillis made four free throws and Elijah Wilson one to offset a 3-pointer and layup by Tyler Strange. The Bulldogs (19-14) had two good looks at 3-pointers in the final seconds but missed both.
Wilson scored 13 points and Tristian Curtis 11 for Coastal Carolina.
CCU, which led from the opening minute, shot 50.9 percent and had a 41-28 rebounding advantage. The Bulldogs stayed close by making 22 of 30 free throws.