CLEVELAND (AP) — Jayson Tatum scored 33 points with LeBron James watching from a courtside seat and the Boston Celtics beat the severely short-handed Cleveland Cavaliers 109-102 in Game 4 on Monday night to take a commanding 3-1 lead in their East semifinal series.

Jaylen Brown added 27 for the Celtics, who can close out Cleveland with a win in Game 5 on Wednesday night at home.

Game 6, if necessary, would be back at Rocket Mortgage FieldHouse on Friday.

The Cavs got pushed to the brink of elimination with two top players in street clothes on the bench, as Donovan Mitchell (calf) and Jarrett Allen (ribs) sat out with injuries.

It was nothing new for a Cleveland team that dealt with injuries all season, but it was a big ask for the Cavs to try and survive without Mitchell, their All-Star guard who has carried the offensive load throughout the postseason, or Allen, their leading rebounder.

The top-seeded Celtics, who have shown a tendency to relax at the wrong time, didn’t show the Cavs much mercy.

Tatum had his second straight strong performance, adding 11 rebounds and five assists. Jrue Holiday had 16 points for Boston.

Darius Garland scored 30 and Evan Mobley and Caris LeVert 19 apiece for the Cavs, who stayed connected with the Celtics and only trailed by 10 going into the fourth.

Boston went up 15 on a jumper by Brown, but Cleveland responded with a 10-2 run as Garland and Dean Wade made 3-pointers.

The Cavs were still within 102-97 when Brown buried a 3-pointer with 1:08 left and Boston closed it out at the free-throw line.

James, who played 11 seasons in two separate stints for Cleveland, was back in his former home arena — a visit certain to drive speculation about where he might play next.

The NBA’s career scoring leader can opt out of his contract with the Los Angeles Lakers this summer, and James has said he’s not made any firm decisions.

The 39-year-old sat across from Boston’s bench in between his wife, Savannah, and agent Rich Paul. James got a monstrous ovation from Cleveland’s crowd when he was shown on the scoreboard during a timeout in the first quarter.

Despite dealing with a left knee injury for months, Mitchell averaged 29.6 points in the first 10 playoff games — scoring 50 in a Game 6 loss to Orlando.

He injured his calf in the waning moments of Cleveland’s loss in Game 3 on Saturday and was added to the injury report as questionable on Sunday. Mitchell underwent round-the-clock treatment but didn’t have enough time to heal.

Allen sat out the seventh straight game with a painful injury the center sustained in the opening round.

With Holiday scoring seven straight points, the Celtics went ahead by 13 in the second quarter and appeared ready to run away from the Cavs.

But Cleveland stormed back as Max Strus, who has struggled with his outside shot throughout the playoffs, made consecutive 3-pointers in a 13-3 run that helped the Cavs close within 62-57 at halftime.

Boston’s center Kristaps Porzingis missed his fifth straight game, but the Celtics were encouraged he was able to do some on-court work.