Jimmy Butler posted a double-double of 35 points and a game-high 12 assists, and the Miami Heat never trailed after a 15-0 first-half run as they extended the visiting Dallas Mavericks’ woes with a 129-122 decision on Saturday.

Miami (41-37) built a lead of as many as 18 points before halftime thanks to its big run, which spanned the final 2:15 of the first quarter and the first 1:17 of the second.

The Heat’s blistering 15-for-26 shooting in the first quarter outpaced a solid 12-of-22 for Dallas. Both teams finished the first half well over 50 percent from the floor — Miami at 26-for-45 for 57.8 percent, the Mavericks at 25-for-40 for 62.5 percent.

Dallas (37-41) chipped away at the deficit in the second half thanks to its hot shooting, particularly from Luka Doncic. He scored a game-high 42 points to lead the Mavericks on a rally that cut the Heat lead to as few as five points in the waning minutes.

It was not enough, however, as Dallas dropped its second straight and sixth in the last seven, dealing another blow to the Mavericks’ hopes of qualifying for the Western Conference play-in. They exit Saturday’s action one game behind Oklahoma City for 10th.

Dallas got key contributions in the loss from Tim Hardaway Jr., who shot 11 of 15 from the floor and 6 of 10 from 3-point range en route to 31 points. Kyrie Irving added 23 points and matched Doncic’s team-high eight assists.

No other Maverick scored in double figures.

Meanwhile, four of Miami’s starting five finished with at least 15 points. Cody Zeller scored 20 points and grabbed eight rebounds filling in for Bam Adebayo (hip), Max Strus scored all 18 of his points on 6-for-9 shooting from 3-point range, and Tyler Herro added 15 points.

Kevin Love came off the bench to add 18 points for Miami.

–Field Level Media