BOSTON — The Eastern Conference finals had been reduced to a best-of-three series, but LeBron James of the Cleveland Cavaliers didn’t look at it that way.

“Nah, it’s a best-of-one series,” James said.

Game 5 on Wednesday at TD Garden had all of that urgency, all of that scrappiness, all of that smothering defense. Larry Nance Jr. of the Cavaliers just may have the scratches to prove it.

But after the Boston Celtics ran off with a 96-83 victory and improved to 10-0 at home in the postseason, it is a best-of-one series. The Cavs must stave off elimination Friday night in Game 6 at home.

Facing the end of a James-led run that includes three consecutive trips to the NBA finals – and perhaps the end of an era if James departs again in free agency – the Cavs slipped back into familiar, destructive habits.

Three of their starters – J.R. Smith (2 points), Tristan Thompson (1) and George Hill (7) – combined for 10 points as the Cavs hit their playoff low in scoring.

Kyle Korver, who has become the Cavs’ third scoring option in the postseason even though he is now coming off the bench, played only 18 minutes and made 2 of 6 field goals, including 2 of 5 from long range.

The Celtics, meanwhile, had five players in double figures, led by Jayson Tatum with 24 points, seven rebounds and four assists. Jaylen Brown added 17 points. Al Horford contributed 15 points and 12 rebounds, and Aron Baynes added six points and seven rebounds.

WHAT DID Marcus Morris say to Larry Nance that ended up sparking a scuffle in Game 5?

Morris won’t say and TV cameras didn’t pick it up. Danny Ainge, the Celtics’ president, was sitting near the play but wasn’t sure what was said.

“You know what? I just thought he yelled,” Ainge said. “I didn’t hear anything. The crowd was so loud and everything I didn’t hear him say anything. I just heard him yell, like ‘Aaaah!’ You know, you make noise on that play. But I don’t know what made Larry Nance so mad.”

One thing did impress Ainge: How fast Celtics Coach Brad Stevens got into the thick of it to break things up.

“I couldn’t believe it,” Ainge said. “I stood up and Brad was already there. It was the quickest move of the night.”

Morris and Nance were hit with technical fouls, as was Terry Rozier, who shoved Nance as things came to a boil.

AFTER STARTING Morris for the first four games of the series, Stevens went with Baynes at center with Horford moving to power forward.

Stevens, who in past years revealed his starting lineup in pregame press conferences, has declined to do that this postseason.

“I don’t think I knew the rules,” said Stevens. “Nobody told me the rules when I got here. They just sent me out here to do the media sessions before every game and nobody said I didn’t have to say it. I guess I’m learning every day.”

KYRIE IRVING, out for the season after two procedures on his left knee, has kept a low profile in the series against his former team. Prior to Game 5, Stevens was asked how Irving was doing.

“In our sitdowns, or just our casual conversations, he seems to be in a great place,” said Stevens. “It’s killing him not to be out on the floor. But I think that would be the case, obviously, any time you’re playing this deep into the playoffs, especially in a new place.”