James followed Game 6’s dismantling of the Celtics with another dominating performance in Game 7 Saturday night, finishing with 31 points and 12 rebounds, and playing all but 28 seconds of the Heat’s series-clinching win.

“We were saying to each other, it’s time,’’ James said. “Let’s play our fourth-quarter defense, what we’re capable of doing. I’m glad we were able to do that.’’

While Game 6 was marked by James’s wall-to-wall display of power, in Game 7, James exhibited a cool control, with more and more big plays as the game went on. As the Celtics’ game began to erode in the fourth quarter - whether because of fatigue or shots just not falling - James continued to rise.

“I really thought he, in particular, played a very smart aggressive game,’’ Celtics coach Doc Rivers said. “He kind of let the game come to him, and then down the stretch he took the game over. That’s what great players do.’’

Many of his biggest plays were ones that didn’t show up so much in a stat sheet.

James had only one block, but it was delivered with such force it sent Rajon Rondo tumbling into the photographers behind the basket. James had just one basket from beyond the arc, but the 30-foot jumper with 5:44 left in the game put the Heat up by 7.

“LeBron takes a shot from halfcourt, it felt like, and makes a 3,’’ Rivers said. “I thought that was a back-breaker for us.’’

The Celtics - and Brandon Bass specifically - did their best to contain James. He had 14 points at the half, but his 11 fourth-quarter points were telling not only of his determination, but of a Boston team that could only hold him back for so long.

“He was brilliant this series and we all know it,’’ said Heat coach Erik Spoelstra. “He’s playing at an historic level during the playoffs, driving us with his will. We do not take his talent or will or his competitiveness for granted. And we need every single bit of it. He is pushing himself beyond his limits, and he’s pushing the rest of the team as well.’’

Rivers had an extended exchange with James after the game, that at first he joked was his attempt at illegally recruiting the NBA’s MVP, but shared that the conversation was an encouraging one.

“He told me he’s very proud of the team and everything,’’ Rivers said. “And I basically told them to go do it; proud of him. I think, again, he gets too much heat.’’

James’s teammates weren’t surprised he was able to showcase his talent in the two biggest games of the Heat’s season.

“He doesn’t have to step outside of who he is,’’ Chris Bosh said. “He’s the best basketball player in the world. He just has to show up and do what he’s been working on and believe in himself, because we believe in him. If he does that, we all like where we stand when the smoke clears.’’