The Tigers (22-9, 11-7 Southeastern Conference) earned their fourth straight win and biggest of the season in a packed Auburn Arena.
The Vols (27-4, 15-3) could have clinched at least a share of the SEC regular-season title with a win but now need No. 10 LSU to lose to Vanderbilt. They have never won back-to-back league crowns.
“A year ago, you think about it, we win the league with five losses,” Tennessee coach Rick Barnes said. “This year we only have three. You have to learn from this. Some of the mistakes we made today, we can’t make. Not at this time of year.”
Samir Doughty collected a long rebound and made a 3-pointer to beat the shot clock. Harper hit two free throws with 31 seconds left for an 80-74 cushion, and Jordan Bone’s 3-point attempt at the other end didn’t fall.
Tennessee’s Grant Williams got the rebound and drew a Flagrant 1 foul from Anfernee McLemore. Williams made two free throws with 23 seconds left and the Vols got another possession. Williams launched a quick basket off the inbounds play.
But Harper hit two more free throws with 20 seconds left for an 82-78 lead.
Bone then missed a 3-point try and teammate Jordan Bowden couldn’t control the rebound, which went out of bounds.
Doughty hit two more foul shots for the Tigers. They celebrated moments later, with Bryce Brown climbing on the press row table in front of the student section after his final home game.
Chuma Okeke led Auburn with 22 points, one shy of his career high. Harper had 16 points and eight assists, with his only two 3-pointers coming back to back in the final minutes. Brown also had 16 points and made four 3s.
Williams finished with 25 points and nine rebounds for the Vols. Bone had 17 points and Bowden 16. Admiral Schofield scored 13 before fouling out.
Tennessee and Auburn teams shared the SEC regular-season title last year and Auburn spent six weeks ranked in the top 10 before falling from the rankings.
Auburn relished the spoiler role this time. The Tigers needed South Carolina to lose to Georgia to earn the No. 4 SEC seed and a double bye in the league tournament.
Tennessee: A 28th victory would have tied for second-most in program history. The Vols’ four losses have come by a combined 15 points. They outrebounded Auburn 39-27.
Auburn: Finished regular season 2-5 against ranked opponents. Had perhaps its best all-around performances of the season.
Tennessee gets a double bye before opening SEC tournament play in Nashville.
Auburn heads to Nashville hoping to improve its NCAA tournament seeding.