Houston led by two points before Blake took the inbounds pass from Jodie Meeks and made the shot to win the game. The Rockets had a chance to win it at the buzzer, but Patrick Beverley's 3-point attempt bounced off the backboard.
James Harden had 35 points and Howard finished with 15 points and 14 rebounds against his former team. Howard missed seven free throws in the last 3 1-2 minutes that could have secured the win for Houston.
Howard spurned the Lakers to sign an $88 million deal with Houston, joining Harden and a team that made the playoffs last season for the first time since 2009.
Meeks, who led the Lakers with 18 points, made a 3-pointer with less than 2 minutes remaining to cut the lead to two and set up Blake's game-winner.
HEAT 102, CLIPPERS 97
MIAMI (AP) — Dwyane Wade scored 11 of his 29 points in the fourth quarter and Miami held off the Clippers.
LeBron James added 18 points for the Heat (4-2), who won their third straight and extended their club record by scoring at least 100 points in a sixth consecutive game to start the season. Chris Bosh, playing for the first time since his wife delivered a baby earlier this week, finished with 12 points for Miami.
Blake Griffin had 27 points and 14 rebounds for the Clippers (3-3). His dunk with 31 seconds left got the Clippers within four, but Griffin allowed about 15 seconds to run off the clock without fouling James on the ensuing possession.
James made one free throw to push Miami's lead to five, and that closed the scoring.
J.J. Redick scored 15 points, Jamal Crawford added 14, Chris Paul finished with 11 points and 12 assists, and DeAndre Jordan had 11 points and 14 rebounds for the Clippers.
Ray Allen scored 12 points for Miami, which got 10 from Chris Andersen.
NUGGETS 109, HAWKS 107
DENVER (AP) — Ty Lawson had 23 points and eight assists and Denver held on to give new head coach Brian Shaw his first win.
Nate Robinson added 15 points and JaVale McGee had 14 for Denver (1-3), which rallied from eight points down in the fourth quarter before surviving a late Atlanta rally.
The win leaves Utah (0-5) as the NBA's only winless team.
Paul Millsap scored a season-high 29 points and grabbed 10 rebounds for the Hawks but missed a short jumper that would have tied the game with 1.9 seconds left. Al Horford, who had 21 points, grabbed the rebound but his shot was off as time expired.