CLEVELAND — Donovan Mitchell has lacked his customary explosiveness and not looked like himself through three games of the Eastern Conference finals. Something seems off with the All-Star guard.

They may soon have time to heal. Like all summer.

Cleveland is on the brink of elimination.

The Cavs couldn’t match New York’s force, firepower or balance despite being on their home floor and lost Game 3 to the Knicks 121-108 on Saturday night to fall into a perilous postseason hole in the best-of-seven series.

No team in NBA history has ever come back from an 0-3 deficit, and the Cavs aren’t showing signs of becoming the first in 164 tries.

Mitchell did what he could, scoring 23 points. But he didn’t have his burst and committed five of his team’s 18 turnovers as the Cavs couldn’t contain the Knicks, who were cheered on a by a raucous group of New York fans that invaded Rocket Arena.

Following the game, Mitchell sat in a chair behind the table before his media interview and stared blankly at a box score underscoring New York’s dominance.

Asked what it’s going to take to avoid a sweep and win Game 4 on Monday night, Mitchell was succinct.

“Let’s start with making some shots,” he said. “Let’s start with getting some stops and making some free throws.”

Mitchell’s first trip to a conference final after so many second-round exits hasn’t gone as hoped. The Cavs, who were pushed to seven games by Toronto and Detroit earlier in the playoffs, blew a 22-point lead in the fourth quarter and lost Game 1 at Madison Square Garden.

They battled for much of Game 2 before fading and are now dragging physically after weeks of playing every other day. The Knicks, who had time to rest after sweeping Philadelphia in the second round, are taking advantage of Cleveland’s heavy legs.

“We did it to ourselves,” Mitchell said. “We can’t be mad now.”

Just as in the first two games, New York was the more aggressive team in the early going, jumping to a 9-1 lead in the opening two minutes and forcing Cavs coach Kenny Atkinson to call a timeout. The Cavs regrouped, but their sloppiness combined with New York’s ability to get out in transition and score proved too much.

“Their physicality and energy level was higher than ours,” Atkinson said. “They were the more physical team and we couldn’t get to that level. Whatever the stats say, they were the better team. They’re playing great basketball. They’re on a hell of a run and we haven’t been able to stop the momentum.”

The Cavs had seized it in the series opener before a stunning collapse that has already provided Mitchell with a lasting lesson.

“Don’t lose Game 1 after being up 22,” he said when asked about what’s soured his conference final debut. “But hey, it happened and now we have to find a way to get back from 3-0. We just have to find a way. We were up 22. It’s on us.”

In the closing minutes, thousands of blue-and-orange-clad New York fans were hollering “Knicks in 4!” and serenading Knicks guard Jalen Brunson, who scored 30 points and added six assists, with chants of “M-V-P” at the foul line.

Those moments normally belong only to Mitchell in Cleveland. But the Knicks are taking everything away from the Cavs. Mitchell said the noise wasn’t unexpected.

“I’m from New York, this doesn’t shock me,” he said. “They do it in every arena. It’s like (Dallas) Cowboys fans. It’s just who they are. It wasn’t just a Cleveland thing. That’s how Knicks fans are. I was one back in the day. That had nothing to do with what’s going on in Cleveland. We didn’t get it done for our home crowd tonight.”

Before the game, Atkinson described Mitchell’s physical issues as merely “bumps and bruises.” The All-Star, who left the floor for treatment in the first quarter, is now dealing with the mental strain of a deficit that’s probably too large to overtake.

Mitchell, though, isn’t giving up.

“We have an opportunity to get one (win) on Monday,” he said. “Then go back to New York and get one there and come back here.”