Kyle Lowry of the Miami Heat in the fourth quarter of...

Kyle Lowry of the Miami Heat in the fourth quarter of Game 1 against the New York Knicks at Madison Square Garden on Sunday. Credit: TNS/Elsa

Jimmy Butler was supposed to be the Knicks’ biggest worry this playoff series. Kyle Lowry just became the smallest and perhaps most annoying one.

Lowry had 18 points in the Heat’s 108-101 Game 1 win at Madison Square Garden on Sunday. The 37-year-old reserve guard outscored the Knicks’ bench (15 points) and had nine points in the fourth quarter.

Butler was hobbled by a sprained ankle suffered late in Sunday’s game. He was present at shootaround Tuesday, but the Heat held him out of Game 2 at the Garden.

Lowry could be another player the Knicks have to worry about this series. As an NBA champion with the 2019 Raptors, he’s well versed in delivering strong games in the playoffs.

Just ask Heat coach Erik Spoelstra, who saw firsthand what Lowry was capable of when he faced Toronto in 2016.

“It’s one of the reasons we went after Kyle in free agency was because [of] my respect for him and what he’s done in the past,” Spoelstra said. “And from a personal standpoint, the battles that we had in a seven-game series . . . I still can’t get over that.”

The Raptors won that second-round series in seven games with Lowry scoring 36 and 35 points in Games 6 and 7. Now he’s bringing that same resolve to the Heat, which could be trouble for the Knicks.

With Butler out of the lineup, Lowry won’t be shy about stepping up. Despite being just 6-foot, his four blocks Sunday matched the Knicks’ entire total. He also had five rebounds and six assists.

It’s just the latest in a career where he’s come up big in the postseason.

“I got swept a few times, lost in the first round, so you can prepare for the playoffs all season, but it’s just experience, maturity,” Lowry said. “It’s just about going through it, and I’ve been through a lot, and a lot of playoffs in my career. But just got to make sure that you’re always there; no ups, no downs, just stay level at all times.”

Butler, of course, is normally the Knicks’ No. 1 priority. The NBA’s leading scorer this postseason, he had 25 points while adding 11 rebounds, 4 assists and 2 steals in Game 1. However, after getting hurt with 5:05 remaining, he took just one shot — a missed three-pointer — before being subbed out with 23.6 seconds left.

The Knicks defeated the Miami Heat in Game 2 of their Eastern Confernce semifinal series on Tuesday night at Madison Square Garden. NewsdayTV's Steve Popper reports. Credit: Newsday/William Perlman

The Knicks know Game 2 is their best chance to regain momentum in the series, especially with Butler unavailable. But that also means making sure Lowry doesn’t have another big game to add to his playoff resume.

“You’ve got an irreplaceable guy, an unreplaceable guy like Jimmy. If he goes, he goes,” Lowry said. “If he’s not, shoot, we’ve got to find a way to just go out there and do our jobs still. We’ve still got to go hoop.”

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