The opening game of the Miami Heat’s five-game western swing saw the Heat and the Golden State Warriors both come out as losers, with former Heat forward Jimmy Butler hobbling off the floor in the second half with what proved to be a season-ending knee injury.

In his first home game against the Heat since his relocation to the Bay Area following his ugly departure last season, Butler let out a painful scream, went down to the court, and then was assisted to the locker room after a misstep following a bump with Heat guard Davion Mitchell while attempting to catch a pass.

An MRI on his right knee was taken immediately after the Warriors’ 135-112 victory, with it revealed Tuesday morning that Butler had torn his ACL, an injury that typically requires a calendar year to heal and rehabilitate.

“You never like to see a situation like that, especially somebody as tough as he is,” Warriors guard Stephen Curry said.

The Warriors loaded up on 3-pointers in Butler’s late-game absence to hand the Heat their third most-lopsided loss of the season, with Erik Spoelstra’s team moving on to Tuesday night’s game against the Sacramento Kings at Golden 1 Center.

Last February, after previously bypassing Butler’s request for an extension, and then suspending the former All-Star forward for conduct detrimental to the team, the Heat dealt Butler to Golden State, receiving in return from the Warriors forwards Andrew Wiggins and Kyle Anderson and the first-round pick that turned into 2025 No. 20 selection Kasparas Jakucionis, as well as Mitchell from the Toronto Raptors, in what turned into a multiteam deal.

The Heat’s concern, even before Butler had begun acting out amid the failed extension bid last season, was paying a player who would turn 36 before this season over $50 million per season on an extension.

No sooner was the trade completed, then the Warriors committed the two-year, $111 million extension that kicked in this season. For that investment, the Warriors got 30 games from Butler last season, 38 this season, with likely a similar number or even fewer next season.

The extension from the Warriors that the Heat bypassed pays Butler $54 million this season and $56.9 million next season.

With the injury, it means Butler now will not have played more than 65 games in any season since he played 76 with the Chicago Bulls in 2016-17, when he was 27.

After scoring 15 points in Monday night’s first half at Chase Center, Butler wound up limited to 21 minutes, closing with 17 points on 6-of-11 shooting, three rebounds and three assists.

It was Butler’s second appearance against the Heat since last season’s trade. He sat out the Heat’s Nov. 18 victory over the Warriors at Kaseya Center for rest.

His previous appearance against the Heat after the trade came last March in a 112-86 loss at Kaseya Center, when he closed 5 of 12 from the field for 12 points.

Butler offered a smile as he walked off the court and toward the MRI that would define his season.

“Yeah,” coach Steve Kerr said, “he asked the ref if it was two free throws or not. So he was kind of chuckling as he said it.”

But the loss of Butler is a devastating blow that could have the Warriors back on the market ahead of the Feb. 5 NBA trading deadline, as they attempt to salvage the closing acts of Curry’s career.

“You really can’t replace Jimmy,” Warriors guard Buddy Hield said. “But as we all know it’s always next man up. You can’t pout, you can’t put your head down. Another opportunity for somebody to step up. Everybody has to step up and do more.

“Jimmy’s one of the guys that can get us to the foul line a lot, he’s our aggressor, but he’s a smart basketball player. You’ve got to be willing to take on that challenge, which is what the NBA brings. It’s an 82-game season. There’s always a challenge within the challenge.”

Butler had been solid this season in support of Curry, averaging 20.0 points, 5.6 rebounds and 4.9 assists, missing only six of Golden State’s first 44 games. His early efforts Monday helped the Warriors improve to 12-4 over their last 16 games, with the Heat falling for the fifth time in seven games.