USC shot 57.8 percent (26 of 45) from the field, including a clip of 68.2 percent (15 of 22) in the second half. It shot 11 of 21 on 3-pointers and was 26 of 33 from the free-throw line.
"That was a battle from start to finish and I thought it was two very good teams playing at high levels today," USC coach Andy Enfield said. "That was a great college basketball game today, and I'm not just saying that because we won. Obviously we're fortunate and we're happy that we won, but I thought that they played at a high level as well."
Metu, a 6-foot-11 junior forward, made 11 of his 15 field-goal attempts and grabbed nine rebounds.
Middle Tennessee held a 66-64 lead after Nick King's reverse layup with 7:42 left to play. However, Boatwright's 3-pointer from the left wing ignited an 11-2 run for a 75-68 USC lead.
There were eight ties and five lead changes. Middle Tennessee led at halftime 43-42.
It was the first meeting between the schools.
Middle Tennessee: King continued his string of scoring in double-figures in every game this season. The 6-foot-7 senior forward entered the contest averaging 22.4 points per game and has eclipsed the 20-point mark in eight of 11 games.
USC: After he was ejected for drawing a flagrant-2 foul in Friday's quarterfinal win over Akron, Boatwright saw 37 minutes of court time in his return against the Blue Raiders. The 6-foot-10 junior forward shot a mere 4 of 11 from the field, but made three 3-pointers and 12 of his 16 free throws to go along with six rebounds, six assists and two blocks.
"I thought he was great. He was efficient, he made the right decisions -- he had six assists -- he got to the foul line 16 times, so he put the ball on the floor, he drove it hard, he posted up and then he made 3s when he was open," Enfield said of Boatwright.
Johnson missed a straightaway 3-pointer for Middle Tennessee, but Karl Gamble came across the lane and elevated before throwing down a thunderous right-handed dunk tie it at 37.
Middle Tennessee: The Blue Raiders held the edge in both points-off turnovers (19-7) and second-chance points (14-4), but attempted nine fewer free throws than the Trojans.
"They're a talented group, a good team and I thought it was a heck of a college basketball, but the whole difference if you look at the stats was just the free-throw line," Middle Tennessee coach Kermit Davis said. "I mean, when you get outscored 26 to 11, that's the game."
USC: The Trojans, who are in the midst of playing eight games in 18 days, improved to 5-0 all-time in the Diamond Head Classic. They won the inaugural edition of the tournament in 2009.
Middle Tennessee will play in the third-place game Monday.
USC will try for its third straight win in the title game Monday.