After Nick Cook's dunk gave the Gamecocks (1-1) a 47-46 lead, Williams, who finished with 16 points, hit a 3-pointer and another basket to make it 52-46 with 2:54 remaining.
Rackley, who led Jacksonville State with 17 points, hit five free throws in the final minute and Williams added two.
The Gamecocks led by 10 points, 36-26, early in the second half before the Eagles (1-1) rallied to take a 44-43 lead with 6:42 left on a jumper by Daylen Harrison, who finished with 14 points.
Derek Thompson, who made four 3-pointers in Eastern Michigan's win over Rochester College in its opener, made two during the Eagles' surge.
Jacksonville State made just 3 of 19 behind the arc in the game.
Sebastien Bellin's friend Chris Young joins Ryan Smith on Outside the Lines to discuss his friend's bravery, courage and strength after surviving the Brussels bombings in March.
Andrew White III is leaving the Nebraska men's basketball team and will play elsewhere for his final college season.
A cameraman fell down trying to film Ben Simmons at the NBA Draft. Flashing back to his LSU days proves this is nothing new.
|Southeast Missouri State||2-14||8||5-24|