South Carolina won its second straight game at the Southeastern Conference tournament, upsetting Arkansas 71-69 on Thursday behind 17 points from Sindarius Thornwell and likely knocking the Razorbacks out of the NCAA tournament.

The Gamecocks (14-19), whose only hope of making the NCAAs is to win it all in Atlanta, advanced to the quarterfinals Friday against Tennessee. Arkansas (21-11) will likely have to settle for an NIT berth.

After South Carolina went ahead 70-69 on Brenton Williams' free throw with 53 seconds remaining, Arkansas squandered two chances to reclaim the lead. Rashad Madden missed a floating jumper in the lane with 33 seconds left, and Bobby Portis one-hander in the lane rolled off the iron with 3 seconds to play.

The Gamecocks missed three of their last four free throws, giving Arkansas one more opportunity. Madden's desperation heave from just inside the half-court line bounced off the back of the rim.

The Razorbacks didn't hide their anguish when the horn sounded.

Madden hustled off the court, Portis grimaced at all the opportunities lost, and Anthlon Bell walked slowly along the sideline with both hands locked on top of his head.

Coty Clarke led Arkansas with 13 points, Portis and Madden had 11 each, and Michael Qualls chipped in with 10. It wasn't enough, the Razorbacks picking the worst possible time to lose back-to-back games for the first time in nearly six weeks.

Laimonas Chatkevicius had 16 points and seven rebounds for South Carolina. Duane Noce added 11 points, Williams had 10 and Mindaugas Kacinas was a force in the lane with 10 rebounds. Michael Carrera also had seven rebounds; no Arkansas player had more than five.

The game was close throughout, the margin never more than six points and within four points throughout the second half.

The Razorbacks appeared to be closing in on an NCAA bid when they won six in a row beginning in mid-February. But Arkansas turned in perhaps its worst performance in the regular-season finale, a 25-point blowout by Alabama, and a one-and-done at the Georgia Dome likely finished off their hopes.

South Carolina was coming off a dominating win against Auburn in the opening round of the tournament; the Tigers fired coach Tony Barbee after the game before the team even left Atlanta.

The undermanned Gamecocks showed some spunk down the stretch, also knocking off Kentucky in a major upset and playing through a one-game suspension for coach Frank Martin after he berated one of his players with an obscenity filled tirade.

Martin barely said a word Thursday, watching his team dominate on the boards (40-24) and mostly do a solid job of dealing with Arkansas' pressing, trapping defense. The Gamecocks did have 15 turnovers, but they weren't shy about taking it to the hoop, drawing 28 fouls and hitting 30 of 41 at the line.

That was essentially the difference. Arkansas made 20 of 26 free throws.