CLEVELAND (AP) — The Boston Celtics defeated the severely undermanned Cleveland Cavaliers 109-102 in Game 4 on Monday night to establish a commanding 3-1 lead in their East playoff series. Jayson Tatum scored 33 points while LeBron James watched from a courtside seat.

The Celtics can eliminate Cleveland with a victory in Game 5 on Wednesday night at home thanks to Jaylen Brown’s 27 points.

If needed, Friday’s game would return to Rocket Mortgage FieldHouse.

Due to injury, Donovan Mitchell (calf) and Jarrett Allen (ribs) were forced to sit the game, pushing the Cavaliers to the verge of elimination.

Although Cleveland had struggled with injuries all season, it was a significant ask for the Cavs to attempt and make it through the semifinals without Mitchell, their All-Star guard who has led the club in scoring, or Allen, their top rebounder.

The top-seeded Celtics, who have a history of letting up when it’s most convenient, showed the Cavs little tolerance.

Tatum added 11 rebounds and five assists to his impressive effort, which was his second straight. For Boston, Jrue Holiday scored sixteen points.

The Cavs kept in touch with the Celtics and trailed by just 10 points entering the fourth quarter, thanks to 30 points from Darius Garland and 19 apiece from Evan Mobley and Caris LeVert.

After a jumper by Brown put Boston up 15, Garland and Dean Wade of Cleveland answered with a 10-2 run.

With 1:08 remaining, Brown made a 3-pointer to keep the Cavaliers within 102-97, and Boston sealed the victory at the free-throw line.

James, who spent two different spells of 11 seasons playing for Cleveland, was back in his old home arena, a visit that would undoubtedly fuel rumors about his potential next destination.

The Los Angeles Lakers’ deal allows the NBA’s all-time leading scorer to opt out this summer, though James has stated he hasn’t made a definitive choice.

The 39-year-old was seated between agent Rich Paul and his wife, Savannah, across from Boston’s bench. During a first-quarter timeout, James was displayed on the scoreboard, to the raucous applause of the Cleveland crowd.

Mitchell scored 50 points in a Game 6 defeat to Orlando despite a left knee injury that kept him out of the game for months. In the first ten playoff games, Mitchell averaged 29.6 points.

In the final seconds of Cleveland’s Game 3 loss on Saturday, he suffered a calf injury. On Sunday, the ailment was listed as questionable. Mitchell received 24-hour care, but his recuperation was impeded.

After suffering a severe injury in the first round, center Allen missed his seventh consecutive game.

After Holiday scored seven points in a row, the Celtics led by 13 points in the second quarter and seemed to be in complete control of the Cavaliers.

However, Cleveland surged back as the Cavs closed within 62-57 at halftime thanks to consecutive 3-pointers from Max Strus, who has struggled with his outside shot during the playoffs, in a 13-3 run.

Kristaps Porzingis of Boston missed his fifth straight game, but the Celtics were happy that he was able to get some on-court practice in.