Denson hit 8-12 field goals and was 3-4 on treys while Harrell made 9-18 field goals while adding six points and six assists.
Another guard, freshman Tajh Shamsid-Deen, iced the contest by making both ends of a one-and-one at the foul line with 17 seconds left to put the Tigers up by five points. Twelve seconds earlier Harrell had nailed both of his foul shots in a one-and-one situation.
Auburn improved its record to 11-9 overall and 3-6 in the SEC while South Carolina to
It was the Tigers' first road victory of the season. "I am proud of the guys to be able to crack that code and get that win," Coach Tony Barbee said.
"The guys fought their tails off from start to finish," the coach added. "You always want that 20-point win on the road, but they are a good team and you knew they are going to make a run. They are well-coached."
Leading by three at halftime the Tigers came out hot and built the lead to 60-44 with 13:18 left to play.
After that the hometown had its own hot streak led by senior guard Brenton Williams, who led all scorers with 29 points. At the 7:46 mark the Gamecocks tied the contest at 62-62, but did not manage to pull ahead.
Denson picked up his fourth foul with eight minutes to play and two minutes later Harrell was whistled for his fourth foul, but both managed to avoid a fifth.
Denson stretched Auburn's lead to 69-63 with a pair of free throws at the 5:35 mark. The closest the home team could get the rest of the way was four points.
For the game the Tigers hit 52.7 percent from the field while making 16-20 free throws and 5-16 threes.
The Gamecocks hit 44.3 percent from the field, 7-17 threes and 13-22 free throws.
Auburn led in rebounding 32-30 and turned the ball over 14 times, two more than the Gamecocks.
Auburn was up 34-27 with 3:07, but the Gamecocks cut the lead to 38-35 at halftime.
The Tigers shot 44.1 percent from the field in the first period and hit 6-8 free throws and 2-10 threes. The Gamecocks hit 44.4 percent from the field and made 8-14 free throws and 3-11 treys.
Shamsid-Deen scored 12 points for the Tigers while senior forward Allen Payne added nine points and nine rebounds.
The Tigers return to action with a Saturday game at LSU.
Stat of the Game: The Tigers outscored the Gamecocks 17-12 in fastbreak points.
Worth Noting, Part 1: Chris Denson scored his 1,000th career point at Auburn with a free throw at the 3:07 mark of the first half.
Worth Noting, Part 2:The Tigers shot 66.7 percent from the field in the second half.