Adams went 7-of-10 from the foul line, while Bellfield added six assists and three steals.
After San Diego took a 58-57 lead with 2:34 left in the game, the Rebels scored the next six points and hung on down the stretch, where they went 8-of-10 from the foul line in the final 2:18.
Rob Jones led San Diego with 19 points, 10 rebounds, and 4 assists. Brandon Johnson added 14 points, on 8-of-9 shooting from the foul line. The Toreros were playing without senior center Gyno Pomare, sophomore forward Clinton Houston, and sophomore guard Trumaine Johnson, who all are serving suspensions for unrelated violations of team rules.
Joe Darger added 10 points and seven rebounds for the winners.
There were 17 lead changes and seven ties in the game, where neither team built more than an eight-point lead.
The Rebels from 3-point range were 8-of-29 (27 percent), while the Toreros were 4-of-16 (25 percent). San Diego from the free-throw line converted 16-of-19 (84 percent), while UNLV was 17-of-25 (68 percent).
UNLV jumped to a 12-4 lead and led 34-29 at hafltime.
Both teams were winners of their conference tournaments and won a game in the NCAA Tournament last year. UNLV captured the Mountain West Conference tourney, while the Toreros won the West Coast Conference. The Rebels won last year at San Diego, 66-55.
Former Kentucky guard Ed Davender, the only Wildcat with at least 1,500 points and 400 assists, has died. He was 49.
Guard Naz Mitrou-Long, whose 2015-16 season ended in December due to hip problems, has been granted a hardship waiver for the coming season, Iowa State said.
As the Sooners look to life without superstar Buddy Hield and his sidekicks, it's clear their unseasoned players will need to grow up fast.