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.
The dust has settled, players having decided whether they are headed to the NBA or back to college. Who won? Who lost? Well, Villanova is pretty happy. USC, meanwhile, not be as thrilled.
The 2017 recruiting class is short on point guards, with Trevon Duval leading only eight prospects from the ESPN 60 who are still available.
ESPN college basketball reporter Andy Katz looks into the two decommitments from the NBA draft and what they're looking forward to.
|Southeast Missouri State||2-14||8||5-24|