BOSTON -- When Marcus Morris dubbed himself one of the best LeBron James defenders in the NBA on the eve of the Eastern Conference finals, even Celtics fans wondered if it was wise to poke the bear.
Shifted into the Celtics' starting lineup for Game 1 and tasked with being the team's primary James defender, Morris backed up his talk while helping Boston to a 108-83 triumph over the Cleveland Cavaliers at TD Garden on Sunday.
Neither Morris nor Boston's revolving door of James defenders were perfect. But they made James work, and the Celtics' late first-quarter scoring barrage gave the hosts the cushion they needed to strike first in this series.
Morris defended James on a team-high 39 possessions, according to Second Spectrum data. The Cavaliers averaged a meager 89.7 points per 100 possessions with that matchup, well below their glossy offensive rating of 108 for the postseason.
"It's a team effort, man. It's not just me," Morris said. "Everybody played their part in guarding him. He's obviously the best player in the game, and you need multiple guys and a team to guard him an entire game. I just think we did a great job of that."
Morris seemed to put his neck out with his comments Saturday, even if he otherwise showered James with praise before remarking about his own defensive prowess.
He said his competitive side led him to seek out the challenge of defending James.
"I'm a competitor," Morris said. "He's the best player, you know? I'm going to be able to tell my kids [about defending James] one day. It's exciting. I love the challenge, but like I said, man, it's a team effort."
Morris, elevated to a starting role as the Celtics went small to match up with Cleveland's small-ball lineup, finished with 21 points on 7-of-12 shooting with 10 rebounds over 34 minutes. He was plus-25 in plus/minus.
James had 15 points on 5-of-16 shooting. He added nine assists and seven rebounds but committed seven turnovers and was minus-32 over 36 minutes.
"I thought they had great game plan Game 1," James said. "[Morris] was the start of it. He was my matchup, and I think they did a great job of communicating throughout the whole game, knowing where I was and knowing where our teammates was.
"[Celtics coach] Brad [Stevens] and the coaching staff did a great job in Game 1. You commend that. We have an opportunity to look at a lot of film tomorrow and see ways they were making us uncomfortable, making myself off-balance and not have a rhythm all game. So we'll be much better in Game 2."
James downplayed Boston's approach, saying he has seen "every coverage" and suggesting that Game 1s have always been a "feel-out game" for him.
Morris, who shot 30.5 percent in the Eastern Conference semifinals against the Philadelphia 76ers, including a 1-for-10 effort in the clinching Game 5, had said he wanted to be more efficient offensively and responded with his best shooting night of the postseason.
"Just playing in the flow of the game," Morris said. "Got a lot of open shots, a lot of easy shots. We just did a great job of moving the ball."
Celtics guard Marcus Smart suggested that Morris' big offensive night might have forced James to expend extra energy.
"[Morris] was able to really force the issue in the offensive end and make LeBron exert so much energy because then he has to come down and really guard him," Smart said. "Can't take plays off against really good players."
Still, it was the way Morris embraced the defensive challenge that resonated most with teammates.
"It's not easy guarding LeBron, but he likes that challenge," Terry Rozier said. "That's something with a guy who likes that challenge, you throw him out there and put him up against him. That's what he did. He took on the challenge and made him work on defense too. It was just good to have him out there, another dog out there with us. He did a lot of good things."
As Morris' comments Saturday confirmed, he doesn't lack for confidence. But maybe that's what makes these injury-ravaged Celtics so unique: They aren't backing down from the challenge of trying to end James' East dominance.
"Our confidence is very high," Morris said. "The younger guys to the older guys, we think we can compete and play with anybody. At the end of the day, all the talking done off the court. Once we step between them lines, we have to compete no matter who we have out there, and that's what we've been doing."