The Nets' James Johnson gets defensive pressure from Marcus Smart...

The Nets' James Johnson gets defensive pressure from Marcus Smart of the Celtics in the first quarter at Barclays Center on Tuesday. Credit: Newsday/J. Conrad Williams Jr.

BOSTON — Marcus Smart knows Kyrie Irving about as well as any player in the NBA. They were teammates for two seasons, opponents for many more. And as a key to the Boston Celtics’ top-rated defense and a front-runner for NBA Defensive Player of the Year honors this season, perhaps there is no one better suited for the task of slowing Irving.

But ask Smart what it looks like for a great defense to face a great offense, and even he said that what you see in the boxscore might not reflect the job that he is doing.

“It’s just making every shot and every possession that he has the ball as hard as possible for him,” Smart said Sunday after the Celtics’ final practice at the Auerbach Center to prepare for Game 1 of their opening-round playoff series against the Nets. “He’s one of the greatest to do it for a reason. We understand that we’re not going to shut his water off all the way completely. We understand we’re not going to stop him. He’s going to score. He’s going to make tough shots. But we’re going to make those shots as tough as possible.”

Now the challenge is the immovable object versus the unstoppable force — can the Celtics’ defense contain Irving and Durant? In Smart, there is as well-suited a player for the task as there is in the NBA.

“He’s truly a magician with the ball,” Smart said. “He has what I like to call last-minute moves, where you think you got him and he always finds a way to get out of the situation he’s in. That’s a gift he has. That’s a gift that has proved to be successful for him and he’s mastered it.

“From that aspect of the game, it’s truly amazing to watch him be able to do those things. Being able to play with him as long as I did, get to learn things from him, watch how he plays, vice versa with him, I’m sure we both picked up things from each other. It’s in the back of our minds and we’re going to put [it] on display Sunday.”

The Celtics have the NBA’s top-ranked defensive rating this season (106.2). With Robert Williams III on the court, they have been a force, but he will be sidelined at least for the start of the series with a partially torn meniscus in his left knee. That leaves Smart as the head of the defense and puts more pressure on him. While the Celtics normally rely on a switching defensive scheme, Smart acknowledged that he will have to stick to Irving as much as he can, and his coach agreed.

“We do have some defensive things we haven’t done much this year that can obviously work against them,” Boston coach Ime Udoka said. “So go down the list of adjustments. Those are there. But we rely on what we do first, though, before we try to get too tricky. If they can continue to score against our high-level defenders, we can go to some things. But we’re going to rely on who we’ve been all year. That’s what got us to this point defensively.”

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