Gallinari also grabbed seven rebounds.
The Nuggets, who hold the fifth seed in the Western Conference, took their sixth straight win and 10th in 12 games.
The Lakers, meanwhile, fell 2 1/2 games behind San Antonio in the race for the West's top seed.
Kobe Bryant finished with 28 points, and Lamar Odom added 17 points, seven rebounds and five assists off the bench for the Lakers.
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