Corey Brewer forced overtime for the Nuggets by hitting a layup with 3 seconds left in the fourth period, but Denver eventually fell to a team playing only for pride.
Dallas had its playoff chances wiped out earlier in the week and faced a club battling for a high playoff seeding. The loss dropped the Nuggets into a tie with Memphis for the No. 3 seed in the Western Conference. Either Denver or Memphis will miss out on home-court advantage in the first round of the playoffs.
Dirk Nowitzki led Dallas with 22 points and Mayo had 20. It was Mayo's 3-pointer with 2:40 left in the extra period that gave the Mavericks the lead for good.