CLEVELAND -- LeBron James gifted himself a grade of F for his birthday.

Despite falling two rebounds shy of his 46th career triple-double, James blasted his own play as the Cleveland Cavaliers barely held on for a 124-118 victory over the Boston Celtics after blowing an 18-point lead in the fourth quarter.

The Cavs needed 32 points from Kyrie Irving, including a pair of driving layups in the final minute, to fend off Boston after entering the fourth with a 101-83 lead. James had 23 points, 11 assists, eight rebounds, eight turnovers and one bad mental lapse late in the game that kept the Celtics' hopes alive.

"I was horrible tonight," James said. "In every facet of the game, I was just pretty bad and it's unacceptable."

James, who turns 32 on Friday, went so far as to address his teammates following the game because of the way he played. After Jae Crowder's 3-pointer pulled the Celtics within 113-108 with 3:26 left, James half-heartedly tapped the ball back to Irving after receiving the inbounds pass. Avery Bradley was lingering in the area and stole it for the easy dunk that pulled the Celtics within three.

"I just didn't see him," James said. "Definitely got to pay attention to what's going on in the flow of the game. I was just throwing it back in to Kyrie and he just jumped it, so if I was paying attention to him, with Avery being the defensive-minded guy he is, I should have seen him. Big mistake."

Irving, who also passed for 12 assists to register his fifth double-double in his last seven games, laughed at James' self-assessment.

"That guy is so special. He gives himself an F and he still ends up with 23, 8 and 11," Irving said. "I understood just from the amount of expectations that he puts on himself every single night. He took full accountability just like anyone else in this locker room would, but as the leader of this team, we command a lot from him. He understands that, he wants it, he thrives in that and I think it's good."

Irving limped off the floor during a timeout with 53 seconds left and watched the rest of the game from the bench with cramping. He banged knees with James in the first half, then felt cramps in his hamstring and calf on his final basket, which gave the Cavs a 119-116 lead.

Cleveland coach Tyronn Lue said he thought Irving would be fine to play Saturday when the Cavs visit Charlotte, but Irving wouldn't commit to anything until he sees how he feels Friday morning.

The Celtics' bench crew led the fourth-quarter charge against the Cavs' regulars. With a home game Friday against Miami, Celtics coach Brad Stevens cleared his bench in the fourth, and the backups brought the team back. He subbed his starters back in as the Celtics' rally gained momentum.

After James split a pair of free throws to give Cleveland a 120-118 lead, the Celtics had a chance to win it. Stevens elected not to use his final 20-second timeout and instead ran a play that left Crowder with an open look at a 3-pointer from the wing with 8.5 seconds left. Crowder clanked the shot, and Richard Jefferson grabbed the rebound to seal the win.

"I thought it was good," Crowder said. "I had a good look at it. My coaches had confidence in me to make that. I'll step into it a 100 more times."

Isaiah Thomas scored 31 points and Bradley added 23 points for the Celtics, who scored 35 in the fourth to make the game close in the final minutes. That did little to appease Stevens, who was more upset at Boston's lack of defense earlier in the game.

"If they have 100 points after three quarters, you don't have a real chance to beat them," he said. "We've got to play a lot better than that. Our guys did a great job in the comeback, but I was disappointed in the first three quarters."

Kevin Love scored 30 points and grabbed 15 rebounds, including 11 points in the third as the Cavs built a 101-81 lead in the final minute of the quarter before the Celtics fought back. It was reminiscent of a game at Cleveland 10 months ago when the Cavs blew a four-point lead in the final seven seconds and Boston stole the win at the buzzer.

"We give them a good shot every time we see these guys," Crowder said. "They're at the top of the Eastern Conference. It's not wearing on us in any kind of way."

NOTES: Celtics coach Brad Stevens attended a football practice at Ohio State while he was in Columbus for a wedding. Buckeyes basketball coach Thad Matta set it up since Stevens was once an assistant under Matta at Butler. Stevens' wife has a lot of family from Cleveland, and his father went to medical school at Ohio State. ... Stevens said he watched Cavs G Kyrie Irving in high school at an under-18 tryout. "He was ridiculous then, by far the best player on the court," Stevens said. "The guy's always been destined to be one of the better players around. ... On the eve of his 32nd birthday, F LeBron James said he doesn't see many similarities between his game and Michael Jordan's. "Our games are so different," James said. "He was much more of a scorer, and that (age) did a lot of post work at that time. But our games are just different. His body is different. My body is different than his. You recognize the dominance that someone had at that age, but there's no similarities in our game at all."