Lawson finished 10-of-16 from the field overall and distributed 10 assists for the Nuggets, who hold the seventh seed in Western Conference and wrapped up their ninth straight postseason berth.
Kenneth Faried added 18 points and 14 rebounds in the victory.
Shannon Brown drained six 3-pointers and finished with 28 points for Phoenix, which came into the contest with a one-game lead over Utah for the West's eighth and final playoff spot.
The Suns' Channing Frye left with an injured shoulder in the second quarter and did not return.
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