Afflalo netted 26 points and Lawson added 25 for the Nuggets, who tightened their grip on the Western Conference's seventh seed with their second in two nights over the Rockets.
Al Harrington chipped in with 15 points and nine rebounds for Denver.
Goran Dragic and Chandler Parsons scored 21 points each in Houston's fourth straight loss.
The Rockets came into the game clinging to a one-game lead over Phoenix for the eighth and final playoff spot in the West.
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