The 6-foot-8 Harrell, who opted to skip the NBA Draft last spring and return for another season, was unstoppable for the Cardinals in an 81-68 win over Minnesota in the Armed Forces Classic on a Coast Guard Base in Puerto Rico.
"He's one of the best players in the country," U of L coach Rick Pitino said.
Pitino had three players in double figures but said Harrell was the difference-maker in the contest for the Cardinals. He finished with 30 points, seven rebounds and two steals.
Harrell played 38 minutes in the contest.
"We just have a great player in Montrezl Harrell," Pitino said. "Arguably he's one of the premier players in the country -- he's a first-team All-American. When you look at the game, having him was the difference maker."
Harrell, a team captain and leader, talked in the preseason about how his game had improved, noting he spent a lot of time working on his ball handling and shooting.
"It's all about confidence," he said last week. "I'm confident with what I can do and I think that's the biggest difference in my game.
On this night, Harrell hit 9 of 12 from the field and was 3 of 4 on three-point field goals. He was also 9 of 10 from the free-throw line after struggling last season.
"I want to do everything I can to lead this team as far as we can go," Harrell said. "We have a long way to go but it's a start."
Harrell, who set a single-season U of L record as a sophomore with 97 dunks, now has 143 for his career after two dunks in the opener. Pervis Ellison is on top of the list at 162, while Darrell Griffith had 156.