Oklahoma City's Russell Westbrook broke Oscar Robertson's 56-year-old NBA record with his 42nd triple-double of the season, and broke Denver's hearts with a buzzer-beating three-pointer for a 106-105 victory.
That shot eliminated the Nuggets from playoff contention.
Westbrook had 50 points, 15 rebounds and 10 assists, including the Thunder's final 13 points.
Danilo Gallinari scored 22 of his season-high 34 points in the third quarter to lead the Nuggets.
Paul Millsap scored 22 points and Atlanta took advantage of Cleveland's fourth- quarter collapse to overcome a 26-point deficit and stun the Cavaliers 126-125 in overtime
Kyrie Irving scored 45 points for Cleveland, and LeBron James had a triple- double with 32 points, 16 rebounds and 10 assists before the four-time MVP fouled out.
Tim Hardaway Jr. added 21 points to help the Hawks beat Cleveland for the second time in three days.
The defending champion Cavaliers and Boston Celtics are tied at the top of the Eastern Conference with two regular-season games remaining - but the Cavs hold the tiebreaker, should they finish level, after winning the season series.