Marcus Campbell, Jamall Edmondson and Shane Power each had 11 points for Mississippi State (16-4, 4-2 Southeastern Conference), which bounced back from one of its worst losses with the closest of its 10 straight home victories.
Mississippi State won its seven previous games in the Humphrey Coliseum this season by an average of 25 points, but South Carolina wouldn't let this one get away until late.
The Bulldogs didn't even need their star forward for much of their decisive run.
Roberts was resting on the bench for most of a 16-5 run that pushed Mississippi State's lead into double figures for the first time, 60-50 with 7:11 remaining. South Carolina couldn't get closer than six the rest of the way.
Tre Kelley had 22 points and Carlos Powell added 18 for South Carolina (10-6, 2-3), which shot 50 percent from the field but fell to 0-5 on the road. Four of those losses came against teams ranked at the time.
Neither team led by more than six points until the middle of the second half, when Dietrich Slater's 12-footer made it 58-50 during the Bulldogs' game-deciding run.
Slater finished with 10 points, Campbell added 10 rebounds and Roberts had 12 points and 10 rebounds by halftime.
The Bulldogs bounced back from a 49-point loss at No. 22 Alabama which matched the second-worst loss in school history.
In that game, the Bulldogs didn't make a 3-pointer for the first time in nearly four years - mainly because top long-distance threat Winsome Frazier is out for the season - and had lost two of three before playing South Carolina.
But against the Gamecocks, whose 3-point defense ranks among the SEC's worst, Mississippi State got well, hitting 6-of-17 from beyond the arc - including 4-of-9 in the second half.
Mississippi State has won four straight and six of seven against South Carolina in Starkville.
South Carolina Falls To Mississippi State
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