HOUSTON — With two-big lineups in vogue, offensive rebounds considered the game’s most valuable commodity and defensive contact that would draw a flag from NFL referees, the Warriors’ first-round series with the Rockets is a throwback to a time long gone.

The Warriors outlasted the Rockets on Monday night in a grimy 95-85 victory in a Game 1 that was short on free-flowing basketball but had uncalled fouls in abundance.

“It felt like 1997 out there, a completely different NBA game than what we’re used to,” Warriors coach Steve Kerr said.NBA teams scored an average of 96.9 points per game that season, so Kerr’s observation checked out.

In that kind of environment, with prehistoric spacing and a choppy pace, Houston-area native Jimmy Butler looked at home in more ways than one.

In 42 minutes, Butler scored 25 points — including six in the final two minutes — to go along with seven rebounds, six assists and five steals.

That kind of raw production is expected from a man known as “Jimmy Buckets” who averaged over 24 points per game as a postseason assassin for the Miami Heat.

But his impact went beyond just his well-rounded and gaudy stat line.

With the Rockets’ cavalcade of gigantic and bouncy athletes focusing on stopping Curry — something they did not do particularly well — Butler was tasked with keeping Golden State’s offense afloat.

“One of my main roles here is to get the rebound and then slow the game down, swing the ball and make sure everyone gets into their spots,” Butler said. “I think that everybody is cool with that.”

Down the stretch, though, Butler stopped swinging the ball and ramped up his scoring aggression.

With 1:43 left in a game where the Rockets grabbed a whopping 22 offensive rebounds, Butler pulled down perhaps the biggest offensive board of the night when he skied for a putback in traffic.

Playing a leading role in a series that prioritized old-school skillsets, Butler’s methodical game is based on fundamentals, strength and finding crevices in airtight spaces.

With a minute left and the Warriors up by nine points, Butler slammed the door on the Rockets by sizing up Alperen Sengun before nailing a 19-foot midrange jumper in a decidedly ’90s-style isolation possession.

“That last (shot) over Sengun, that’s what we want,” Draymond Green said. “We have to do an even better job of making sure he gets the ball.”

The Warriors have played Butler at least 40 minutes in each of the last three games — a key regular-season finale loss to the Clippers, the play-in win over the Grizzlies and the Game 1 win in Houston. The stats show why.

The Warriors’ offensive rating increases by 7.5 with him on the floor versus when he is off, which is the same margin between the 20th-ranked Chicago Bulls and No. 1 Cleveland.

Putting up gaudy offensive stats will not be easy against the Rockets, who will need to regroup for Game 2 tonight after the Warriors took home-court advantage.

But Butler has shown enough during his 10 weeks with the team to prove that he can be depended on to produce in a throwback series.

“(This is) just a continuation of what it’s been like since he’s been on our team since February,” Curry said. “He has a knack for the big moments, even if it’s not him finishing the play.”