Gay's rush was part of 10 straight points for Memphis, breaking open a 68-68 game with 4:45 left. His 18-footer on the baseline with 1:25 left gave Memphis a 10-point lead, helping the Grizzlies snap a two-game losing streak.
Zach Randolph had 12 points for Memphis, which won despite shooting 40 percent. The Grizzlies outscored the Nuggets 28-15 in the fourth, eventually building the lead to 11 points.
Andre Iguodala, Corey Brewer and JaVale McGee all had 12 points for Denver, which had its two-game winning streak end. Kenneth Faried had 11 points for the Nuggets, hitting 5 of 7 shots.
Danilo Gallinari, who was coming off a career-high 39 points Friday night against Dallas, was held to 7 points on 2-of-8 shooting.
The game was tied at 68 when Gay got took over. He scored on a pair of layups, the second coming on a feed from Randolph. He hit a 12-foot fadeaway before Randolph scored inside.
Gay capped the 10-0 stretch with an 18-foot baseline jumper for a 78-68 lead with 1:25 left.
Wayne Ellington's 3-pointer with 23 seconds remaining gave Memphis its largest lead, 81-70.
Memphis held a seven-point lead in the first half, but needed a jumper from Jerryd Bayless in the final second to hold a 37-36 advantage entering the locker room.
After Memphis built its biggest lead of the half on six straight points by Gay in the second quarter, the Nuggets answered with the next eight points for the lead.
McGee gave the Nuggets their first lead of the game on a dunk with 8.1 seconds left in the half.
Gay led Memphis with 10 points at the break, but the game was rather sloppy as Memphis shot 39.5 percent from the field, compared to 45 percent for Denver. The two teams were a combined 3 of 15 from outside the arc.
No Denver players were in double figures at the half, and Gallinari, who had hit 14 of 23 against Dallas, was scoreless, missing all three of his shots.
That slump ended immediately at the start of the second half as Gallinari connected on a 3-pointer.
The game settled into a close affair after halftime with seven lead changes and five ties in the third quarter alone.
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