Georgetown, the No. 2 seed in the East Regional, is known for the inside power that produced its first Big East Conference tournament title since 1989. Belmont, the 15th seed, collapsed on Big East Player of the Year Jeff Green and 7-foot-2 Roy Hibbert, which left Sapp wide open.
The sophomore guard responded with 20 points and four three-pointers, both career highs. In the first half, he matched Belmont's three threes, which did not bode well for a team that makes nearly nine a game.
"Most teams in the nation aren't going to beat them [Georgetown] when their inside-out game is going," Belmont guard Justin Hare said.
The Bruins got the crowd at Lawrence Joel Veterans Memorial Coliseum on their side by taking an 11-4 lead, but they went eight minutes without a field goal during a 17-1 Hoyas run in which Green scored the tying and go-ahead baskets.
"We've been in a hostile environment before," Hibbert said. "We didn't get flustered."
Green had 15 points, and Hibbert had 13 rebounds and eight of his 10 points in the second half, as Georgetown recorded its most lopsided NCAA tournament win since 1996, when Allen Iverson and the Hoyas beat Mississippi Valley State, 93-56, also in a 2-15 game.
Georgetown (27-6) won for the 16th time in 17 games. Its only loss in the past two months came at Syracuse on Feb. 26. Next up for the team coached by John Thompson III is No. 7 seed Boston College (21-11), in tomorrow's second round. The two were longtime rivals before Boston College moved to the Atlantic Coast Conference.
Belmont, the Atlantic Sun champion, finished 23-10. The Bruins scored 94 in their conference tournament final, but had trouble getting inside against a team that is fifth in the country in scoring defense.
Georgetown's biggest lead came at 59-33, on a free throw by Patrick Ewing Jr.