Celts beat Cavaliers, 96-83, to take a 3-2 lead in the Eastern Conference finals. Game 6 is Friday in Cleveland.

Jim Fenton The Enterprise @JFenton_ent

BOSTON -- They were supposed to be too shorthanded to last very long in the playoffs with two All-Stars sidelined.

Yet here are the Celtics just one victory away from an improbable trip to the NBA Finals.

They have taken a 3-2 lead over the Cleveland Cavaliers in the Eastern Conference finals thanks to a 96-83 victory in Game 5 Wednesday night at the TD Garden.

After limping home from Ohio this week following two losses, the Celtics responded with a strong defensive performance and overcame a poor shooting night to put LeBron James and the Cavs on the verge of elimination.

The Celtics get the chance to move on to the Finals for the first time in eight years on Friday night when Game 6 takes place in Cleveland.

“We did what we were supposed to do,’’ said Al Horford after getting 15 points and 12 rebounds. “We won here, a big Game 5 for us. Now we have a big challenge to go on the road.

“We’re going to have to play a great game come Friday. They’re tough at home. We have to make sure that we’re really focused and committed to playing the right way the whole game. We’ve done it in spurts. We have to be more consistent.’’

The Celtics improved to 10-0 at the Garden in the playoffs, the first time they’ve had that home postseason record since the 1986 championship season.

After struggling in Cleveland, the Celtics made some adjustments – putting Aron Baynes in the starting lineup for more size and figuring out how not to leave Terry Rozier guarding James in pick-and-rolls – and that helped get the edge.

The Cavs never led after the midway point of the first quarter and were behind by as many as 21 despite the fact that the Celtics shot 36.5 percent from the field. That is tied for the fourth-lowest shooting percentage by a winning team in the playoffs in NBA history, according to stats guru Dick Lipe.

The stifling defense made up for that lack of offense as the Cavs were nowhere near as effective as they were in Games 3 and 4.

“We were not the more connected team in Cleveland,’’ said coach Brad Stevens. “That bothered us all, I think. We wanted to come out and defend well.

Said Horford: “We played much better tonight defensively. The energy was much better. I was encouraged by the performance of our group tonight.’’

Rookie Jayson Tatum led the way with 24 points, seven rebounds, four steals and four assists while Jaylen Brown added 17 points. Marcus Morris and Marcus Smart scored 13 each off the bench.

James (26 points, 10 rebounds) and Kevin Love (14) were the only two Cavs to score in double figures as the other three starters combined for 10 points.

“We were in tune defensively,’’ said James. “Offensively, we just couldn’t make it. Defensively we gave ourselves a chance.’’

The Celtics opened a 32-19 lead after one quarter, and after the Cavs made a run in the second quarter, held a 53-42 halftime edge.

The lead was extended to 76-60 going into the fourth quarter and the Celtics, despite struggling with their offense, held on when the Cavaliers made one last push, thanks to the defense.

“It’s our defense,’’ said Horford. “We always preached all year, or coach preached all year, he would say there are going to be nights that we’re not going to shoot it well, but we have to rely on our defense.

“Since the first day of training camp, that’s what we’ve hung our hat on as a group. Tonight it paid off. Defense was the different tonight.’’

It was a completely different performance than what the Celtics had on the road where they are 1-6 in the playoffs.

“I just think at home one of the big things is I truly believe it’s our fans,’’ said Horford. “I feel like our guys feed off of them and that really drives us as a group. The atmosphere that’s here, it’s just a lot of fun to play here right now.’’

Now the Celtics have to figure out a way to have success on the road, or else they’ll be back in Boston for Game 7 on Sunday night, a dangerous proposition with James on the other side.

“To do what we want to do we still have to beat this team one more time,’’ said Stevens. “It’s hard to win a game in the NBA. It takes a ton of preparation, takes a ton of focus, takes a ton of effort. That’s the task.’’