It was the first-ever win in Boulder for the Beavers (14-17, 4-14 Pac-12). They were 0-6 before Nelson closed out a tight game on a layup with 15 seconds remaining, sending the crowd heading for the exits.
Spencer Dinwiddie had 18 points for the Buffs (20-10, 10-8), who were attempting to tie the school record for wins in the regular season, a mark held by the 1996-97 squad that featured Chauncey Billups.
After the game, coach Tad Boyle said to the fans over the loud speaker, "I apologize for today's performance."
For a second straight game, Colorado played without Andre Roberson, who's sidelined with a viral illness. Boyle hopes to have the nation's leading rebounder back on the court in the conference tournament.
Charles Matthews, who spent his freshman season at Kentucky, has picked Michigan as his transfer school, according to a source.
Chad Ford and Jeff Goodman offer their opinions on the surprises they're expecting at the NBA draft, with Ford believing there will be a lot of trade activity while Goodman thinks people will be surprised by potential draft spot of Marquese Chriss.
Louisville coach Rick Pitino said he doesn't "have time to figure out what" Kentucky coach John Calipari meant in recent comments that appeared to be a jab at the Cardinals' program.