Two-time defending NBA champions Miami have now dropped five of their last six games after a 111-107 loss to the Denver Nuggets.
The current stretch matches the worst six-game run for the Heat since the start of the 2010-11 season and puts them three games back of Indiana for the Eastern Conference's number-one seed.
Elsewhere, Jonas Valanciunas had a season-high 23 points as the Toronto Raptors defeated the Memphis Grizzlies 99-86.
Damian Lillard scored 16 of his team-high 27 points in the fourth quarter to lift the Portland Trail Blazers to a 111-103 victory over the New Orleans Pelicans, snapping a four-game road losing streak.
Al Jefferson put on another show with 25 points and 16 rebounds as the Charlotte Bobcats won their third straight game, beating the Minnesota Timberwolves 105-93.
The Indiana Pacers produced a 101-94 victory over the Philadelphia 76ers.
John Wall had 21 points and 11 assists to lead a well-balanced attack for the Washington Wizards, who beat the Orlando Magic 105-101 in overtime.
Alex Len came off the Phoenix bench because of injury and ended up scoring six key points to lead the Suns to an important 87-80 victory over the Boston Celtics.
Guard Danny Green had 15 points, all from behind the three-point line, and the San Antonio Spurs won their ninth straight game with a 119-85 victory over the Los Angeles Lakers.
Forward Blake Griffin scored 20 points, point guard Chris Paul contributed 18 points and the Los Angeles Clippers rallied to beat the Utah Jazz 96-87 for their 10th straight win.
The Cleveland Cavaliers used a 68-39 dominance in the middle two quarters to build a lead and held on down the stretch to surprise the Golden State Warriors 103-94.