Mississippi had trouble shooting but Clemson couldn't keep the Rebels off the glass.
Dwayne Curtis and Chris Warren both scored 19 points to lead the Rebels to an 85-82 victory over No. 15 Clemson on Saturday night in a matchup of unbeaten teams in the championship game of the San Juan Shootout.
"Our undoing was the offensive glass," said Clemson coach Oliver Purnell, whose team grabbed 12 offensive rebounds compared to 23 for the Rebels. "They're a gutsy team, I give them a lot of credit."
Warren and Curtis, who had nine rebounds, went a combined 4-for-5 from the free throw line in the final 90 seconds for Mississippi (11-0), which matched the best start in school history.
The Rebels started 11-0 in 1936-37 and 2000-01.
"Clemson is a very good team, and this is a win we'll be able to hang our hat on deep into the year if we continue to improve because they're going to beat a lot of people," Mississippi coach Andy Kennedy said.
Eniel Polynice and David Huertas both added 14 points for Mississippi.
Terrence Oglesby led Clemson (10-1) with 20 points, including going 5-of-7 from 3-point range, while K.C. Rivers added 19 points and Raymond Sykes had 17.
Warren's layup after a steal by Huertas capped Mississippi's 8-0 run and gave it the lead for good, 80-78 with 2:55 remaining.
"My teammates find me, and I find them," said Warren, who was selected the tournament's most valuable player.
Trailing by eight points at halftime, Clemson took its first lead of the second half at 54-53 on a soaring one-handed dunk by Sykes with 13:15 remaining. But the Rebels kept their composure despite the run.
"I think we've got grinders, and the fact that we've been in this situation before with some close games allowed us to not panic and continue to grind," Kennedy said.
Mississippi opened the game on an 8-2 run capped by Polynice's putback of his own rebound. The Rebels went ahead 41-32 on a 3-pointer by Warren with 3:22 to play in the first half and held on for the 48-40 halftime lead. Curtis was 7-for-7 from the field in the first half when Mississippi outscored the Tigers 34-18 in the paint.
"The difference was our intensity, especially the first five minutes of the game," Curtis said. "There's a lot of things to work on, too, but this shows what we're capable of doing."
Clemson had six blocks and held Mississippi to 27 percent shooting in the second half, but the Rebels dominated the boards overall 39-34 and had 24 second-chance points compared to 11 for the Tigers.
"We just responded down the stretch, stepping up and making big plays," Kennedy said.
A cheering section of family and friends of Huertas, a native of Humacao, Puerto Rico, gave Mississippi the edge in crowd support inside the nearly empty stadium in this suburb of San Juan.