The Boston Celtics fought off a spirited challenge from short-handed Cleveland Monday, beating the Cavaliers 109-102 to take a commanding 3-1 lead in their NBA Eastern Conference semi-final series.

Jayson Tatum scored 33 points and grabbed 11 rebounds and Jaylen Brown added 27 points for the Celtics, who will try to finish off the best-of-seven series at home on Wednesday.

The Cavaliers were dealt a heavy blow when Donovan Mitchell, who had averaged more than 35 points over the six prior games, was ruled out with a calf injury, joining starting centre Jarrett Allen on the sidelines.

NBA superstar LeBron James, who led the Cavs to their only NBA title back in 2016, was sitting courtside, but with Mitchell absent the Cavs ultimately didn't have enough firepower.

The Cavs kept the pressure on, taking the lead briefly on Darius Garland's driving basket early in the third quarter – their first lead since the first quarter.

But the Celtics quickly reasserted themselves and led by 10 going into the final period.

Cleveland, on the back of 30 points from Garland, pulled within five points three times in the final four minutes, but Brown, fed by Tatum, connected on a three-pointer with 1:09 to play that effectively sealed it.

"It's a game of runs," Tatum said after the Celtics struggled to put the depleted Cavaliers away.

"It's not going to be perfect every single time. They're going to make shots, but it's our job to figure it out." (AFP)