Josh Richardson scored 12 points, and Tennessee used a 19-3 second-half run to beat Xavier 51-47 on Saturday night.
The Volunteers (8-3) trailed 33-23 early in the second half before holding the Musketeers (7-5) without a field goal for more than 10 minutes.
Derrick Reese knocked down a 3-pointer with 8:14 left to give Tennessee a 38-35 lead. It was the Vols' first lead since being ahead 7-6 at the 12-minute mark of the first half.
Xavier cut the lead to 44-43 with just over two minutes remaining on Travis Taylor's layup, but a lay-in by Jordan McRae and five free throws by Trae Golden preserved the Tennessee victory.
"We did a great job blocking shots. We did a good job on defense of cutting the lane off, forcing those guys to make the extra plays," Tennessee coach Cuonzo Martin said. "I thought we did a tremendous job, especially in the second half."
The Musketeers led 25-21 at halftime.
Tennessee held Xavier to 32.7 percent (18 of 55) shooting. The Vols shot 38.8 percent (19 of 49), but were just 3 of 20 from 3-point range, continuing their season-long struggles from beyond the arc.
The Musketeers led by as many as eight points in the first half and took a 25-21 advantage into the locker room after Tennessee missed the front end of a one-and-one with 2 seconds left in the opening half.
"Two things allowed Tennessee to get in the game and where we lost momentum," Xavier coach Chris Mack said. "We missed five or six layups around the basket in the second half. That's when we went on that drought. We gave up two wide-open jump shots."
Richardson was the only Vol who scored in double figures, and he had seven rebounds. McRae had eight points, while Jarnell Stokes chipped in six points. Golden, the Vols' top scorer this season, scored five points.
Martin said Golden injured his left shoulder earlier in the week in practice, but he didn't think that affected his shooting.
Reese, who was cleared to play for the first time this season on Friday after undergoing offseason shoulder surgery, provided a spark for the Vols in his college debut, hitting two 3-pointers and scoring seven points.
"It wasn't a question once he was cleared to play - we got that information yesterday - he was playing because I know what he brings to the table," Martin said. "He runs the floor very well. He does a good job. Those are shots he makes in practice."
Tennessee's bench outscored Xavier's 21-9 and played a large role in the Vols' second-half surge.
Taylor finished with 12 points and seven rebounds for Xavier. Isaiah Philmore scored eight points, all in the first half, and grabbed seven rebounds. Semaj Christon, the Musketeers' leading scorer entering the game, had just five points on 1-of-9 shooting.
"We're right there. We're in every game," Mack said. "These are all coming down to one or two possessions, and we've had guys in different roles. We have to find the ability to close games. I'm not going to question my kids' effort.
Xavier controlled the glass, outrebounding Tennessee 44-28, but the Vols had a season-high nine blocks and forced 19 Xavier turnovers, the most for the Vols during Martin's two-year tenure as coach.
"I told the guys at the half I thought this is probably the first time all season where we really got out-toughed," Martin said. "I thought they were the tougher team. They set the tone early. They were physical; they were rebounding. They came ready to play, and it showed in the first half. Our guys were resilient in the second half, found ways to win the game and did a great job getting stops when we needed to."
It was the Musketeers' third consecutive defeat after losing to Cincinnati and Wofford. Xavier travels to Wake Forest on Jan. 2 before starting conference play in the Atlantic 10.
Tennessee hosts in-state rival Memphis on Jan. 4, then begins Southeastern Conference play.