Mikal Bridges is the NBA’s iron man, but in the closing seconds of Monday’s Game 1 win, the Knicks forward embodied an NFL ballhawk.

With 3.0 seconds left in overtime and the Knicks leading by three points, Bostons Celtics guard Derrick White heaved a cross-court inbound pass toward Jaylen Brown.

Brown had set up in the TD Garden backcourt and got a running start as White’s pass met him just outside the 3-point arc.

But Bridges read it.

Bridges followed Brown to his spot, then stuck his hands in as Brown was attempting to gather the wide pass. Bridges ripped the ball away and heaved it down the court as time expired, clinching the Knicks’ 108-105 win.

“I was just watching his eyes,” Bridges said afterward. “I’m a football guy, so I’m just watching his eyes and following where the ball’s at and trying to get my hands [ready] as soon as I see the ball.”

The game-ending steal capped another clutch performance by Bridges, whose relentless defense and late shot-making helped the Knicks erase a 20-point deficit and go up 1-0 over the heavily favored Celtics.

It was the kind of performance the Knicks envisioned last summer when they traded five first-round picks to the Brooklyn Nets to acquire Bridges.

“Mikal came up with some big-time rebounds in traffic, and then the steal at the end,” head coach Tom Thibodeau said. “Whatever we have to do to find a way to win. That’s the most important thing.”

Bridges had three points, two steals and a block in overtime.

The first steal came with 3:29 left in OT and the score tied 100-100. Brown tried to bounce a pass to Al Horford in the corner, but Bridges got a hand on the ball, reached for it with one foot in bounds and completed an acrobatic pass to Josh Hart without stepping on the line.

That sequence set up a transition dunk by OG Anunoby, who was fouled and made the free throw for a three-point play. That basket put the Knicks up 103-100 and proved to be the game-winner.

On the Knicks’ next possession, Bridges drilled a 3-pointer from the corner, getting help from the backboard as the ball glanced off the glass.

“He got big stops,” Anunoby said of Bridges. “He made big-time shots. He just stayed with it, kept playing hard, and you saw the results.”

Bridges, 28, averaged 17.6 points per game on 50.0% shooting in his first season with the Knicks. He appeared in all 82 regular-season games, extending his NBA-best consecutive games streak to 556.

But the lofty price the Knicks paid to get Bridges made him the subject of frequent scrutiny.

That chatter has quieted, however, as Bridges makes key plays this postseason. In the Knicks’ 116-113 win over the Detroit Pistons in last round’s series-clinching Game 6, Bridges scored 25 points on 11-of-16 shooting, including the game-tying tip-in with 35.1 seconds left in the fourth quarter.

On Monday, Bridges finished with only eight points on 3-of-13 shooting, but he played a game-high 51 minutes and added seven rebounds, six assists, three steals and two blocks.

The Knicks invested heavily in Bridges and another defensive stopper in Anunoby to combat a team like the Celtics, whose wing combo of Brown and Jayson Tatum is widely considered the NBA’s best.

Brown and Tatum shot a combined 14-of-43, including 5-of-25 on 3-point attempts, in Game 1.

“That’s who Mikal is. He’s got a lot of criticism and he never lets that affect him,” Knicks guard Josh Hart said after Monday’s win.

“He’s a winning player. He makes winning plays. He should be celebrated for that.”