BOSTON — It’s one thing for a player like Marcus Morris to back up what he said heading into his team’s playoff series against LeBron James.

It’s another thing for him to have said it at all.

Yes, the order of those sentences might seem reversed from what you’d normally expect. And yet Morris — a no-nonsense, 6-foot-9, seventh-year forward for the Celtics — might have contributed as much to Boston’s 108-83 victory by what he said Saturday as by what he actually did Sunday in Game 1 of the Eastern Conference finals at TD Garden.

Morris was terrific as the point of the Celtics’ defensive spear against James, Pest No. 1 for a defensive unit that bothered the Cleveland Cavaliers’ superstar into one of his poorest playoff performances in recent memory.

Having led the Cavs in scoring in each of their first 11 postseason games this spring, and reaching at least 20 points in each, James managed neither: He finished with 15 points on 5-of-16 shooting (0-of-5 on threes), second for a change to Kevin Love’s 17 points. He had seven rebounds and nine assists, but James also was responsible for seven turnovers. When James was guarded by Morris on 24 plays, he scored only five points on 2-of-6 shooting.

And he was a minus-32 in a game his team lost by 25.

Morris capped that performance in his first playoff start for the Celtics by posting a better stats line than the Cavs’ and arguably the NBA’s MVP. In 34 minutes, the native of Philadelphia nicknamed “Mook” scored 21 points on 7-of-12 shooting, hit three of his four 3-point attempts and grabbed 10 rebounds. He navigated early foul trouble, too, sticking around even after he picked up two personals in the first quarter and a third in the second.

I’ve never really been at a point where anybody’s ever broken me with shots or anything like that. I think he’s probably broken Toronto, if that’s what you were referring to. … It looked very easy.

Marcus Morris on LeBron’s dominance over Toronto

And still, for all that in-game, on-the-parquet production, Morris’ most notable move might have come the day before. That’s when he talked about meeting the challenge of guarding James — solo, in tandem or as part of a mob – and didn’t blink.

Other Celtics were watching and listening, after all. Young teammates. Guys for whom the idea of facing the great LeBron James — in his eighth consecutive conference finals, within sniffing distance of his eighth straight Finals appearance — might be a wee daunting.

But there was Morris (gasp!) talking about the matchup and brimming with confidence.

“Personally, I think I’m probably the best guy defending him in the league, outside of Kawhi [Leonard of the Spurs],” Morris said.

He didn’t stop there. He talked about drawing James as his primary cover two years ago, when he was with Detroit and the Cavaliers swept the Pistons out of the 2016 first round.

Morris acknowledged that he and any other Boston player who had to stare into the heart of darkness fending off James would have help and reinforcements. He spoke rather dismissively about Toronto and the dismal way the Raptors handled the guy, as if they were buckling under a steamer trunk’s worth of pressure and intimidation.

Nope, not him, Morris said.

“I’ve never really been at a point where anybody’s ever broken me with shots or anything like that,” Morris had said, dropping in a couple expletives. “I think he’s probably broken Toronto, if that’s what you were referring to. … It looked very easy. He looked very confident. Obviously, he’s always confident, but the things that he did, it looked too easy to me.”

Right there, way out in Waltham, Mass., at the Celtics practice facility a day early and with Cleveland maybe not even in town yet, Morris helped the Celtics toward their Game 1 victory.

Like he said, we’re doing it as a unit. It’s not all on him. But you do have to give him credit for his focus and his commitment.”

Al Horford, on Marcus Morris guarding LeBron James

He looked directly at the elephant in the room, its tusks flashing in full stomp mode, and essentially said, “I’ve got this.”

That’s no routine strategy against James. As is the case with the toughest opponents across all sports, the conventional wisdom always is: Don’t poke the bear or, to keep our metaphors aligned, the elephant.

OG Anunoby, the lanky young guy charged with guarding James for Toronto, might not have said a word before the four-game sweep was over. The Indiana Pacers’ Lance Stephenson? Please. It’s to Stephenson’s credit that he doesn’t seem to get intimidated playing against James, but James pushes back on him and the Pacers with a permanent smirk on his face. It’s a big brother-little brother dynamic all the way.

This, on the other hand, was tough talk from an adult with the brass to back it up. Teammates who may have had their doubts knew instantly who to follow.

“Marcus is one of our leaders and he’s been a presence since the first day he got here,” veteran Al Horford said. “So, I think taking on this challenge is something we expect out of him.

“Like he said, we’re doing it as a unit. It’s not all on him. But you do have to give him credit for his focus and his commitment.”

Said second-year forward Jaylen Brown: “Oh, he was fantastic.”

The only one hedging was done by Celtics coach Brad Stevens. He sounded at times after the Game 1 beatdown as if he wanted to apologize to the Cavs and hide it somewhere. He knows that a bloodied LeBron is a dangerous LeBron, and ditto for the other Cleveland players who have played at this level and beyond.

Stevens’ first response when asked about Morris’ 1-on-1 defensive performance was to credit the group, the secondary helpers who took away James’ driving and passing lanes.

His second response was to ignore Morris’ chatter that helped set such a tone for his team and focus on the errors and failings that might bite in Game 2.

“I don’t pay attention to any of that stuff,” Stevens said. “We’re very alert to the fact that we’ll get a heavyweight punch on Tuesday night.”

I have zero level of concern at this stage … I’ve been down before in the postseason. But for me, there’s never no level of concerns, no matter how bad I played [or] how inefficient I was.”

LeBron James

James — whose resume just about guarantees that type of bounce-back — wasn’t flustered at all afterward. He lavished no particular praise on Morris other than being “the start” of a Celtics’ defensive scheme successful in “making us uncomfortable, making myself off balance and not have a rhythm all game.”

As James sees it, there is no way the Cavaliers miss 22 of 26 3-point shots (and start 0-of-14) again. No way coach Tyronn Lue and his staff draw up another plan that enables Boston to score 60 points in the paint. No way, either, that any one opponent – including Morris – crafts a reputation as a “LeBron stopper.”

There hasn’t been one yet, after all these years, all these exposures, all the scouting and video breakdowns and willing candidates. If there’s one now, in this series, it will grab headlines.

“I have zero level of concern at this stage,” James said. “I didn’t go to college, so it’s not [single-elimination] March Madness. You get better throughout the series.

“I’ve been down before in the postseason. But for me, there’s never no level of concerns, no matter how bad I played [or] how inefficient I was.”

So, Morris isn’t the only one talking tough and brimming with confidence. It’s up to the other Cavaliers to decide how much that imbues them, and with what.

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Steve Aschburner has written about the NBA since 1980. You can e-mail him here, find his archive here and follow him on Twitter.

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