BOSTON - All season, through the ups of a 20-9 start to the downs of pretty much the remainder of the season, when the team went 15-22, 76ers coach Doug Collins talked of growth, of maturity. He spoke of his team learning how to win and how to take something out of the losses. Wins and losses were more about lessons at times than they were about the seasonal record.

Monday, at TD Garden in Game 2 of the Eastern Conference semifinals against the Celtics, Collins' team had a serious mental growth spurt in the fourth quarter, staving off a patented Boston rush and grinding out an 82-81 win that evened the series at one game apiece.

It was fitting that so many of the young players contributed late in the monumental win. With the game tied, 65-65, and 4 minutes, 4 seconds left, the Sixers had the ball, side out of bounds, with just 0.9 seconds on the shot clock. The inbounds pass went to Lavoy Allen, who banked in a lucky 22-footer for a two-point lead.

"When Lavoy hit that shot I thought that maybe we had a shot to win, because baskets were hard to come by," said Collins.

After Avery Bradley hit a three-point jump shot to put the Celtics up, 72-71, and make another collapse down the end of a game seem probable for the Sixers, Jrue Holiday nailed a three-pointer with 1:57 remaining. That shot was matched by Ray Allen at the other end on Boston's next possession for a 75-74 Celtics lead. Evan Turner, who was having one of the worst games of his NBA career, drained a tough driving layup with 40.4 seconds left for a 76-75 lead. The Sixers never trailed again, and return home to the Wells Fargo Center for a Game 3 meeting on Wednesday night at 7 o'clock.

"Our young guys keep growing and now they're becoming men," Collins said. "Our guys are growing up, and in Boston Garden, and playing the Celtics and the greatness this team is, for our guys to just scrap through this game tonight . . . We just found a way. Everybody who came in gave us a great effort. All season long we couldn't win these games and now they believe they can do it, and it's fun to watch."

When two of the better defensive teams in the league play each other, offensive artistry isn't expected to be at its best. Monday proved that, and then some. But the Sixers were a little less ugly, particularly during the third quarter when they outscored Boston by 10. And the defensive effort put forth by Lavoy Allen on Kevin Garnett, who finished with just 15 points, 14 below his Game 1 total, was certainly a difference-maker in the game, maybe for the series.

"I just try to go out there and compete as hard as I can," Lavoy Allen said. "Game 1, he hit a lot of jump shots, a lot of open jumps shots. This game, he tried to do a lot in the post so I tried to push him off the blocks or make him start his post-up a little farther away from the basket so we could try to contain him."

"Lavoy Allen was great," Collins said of his rookie, who posted 10 points and eight rebounds in 30:21. "We tried to put some strength on [Garnett]. We tried to take away his rhythm shots. They do such a great job of getting you strung out and throwing back to him and all those shots he catches in rhythm and he just doesn't miss. So really, it was trying to disrupt the efficiency and the timing just a little bit. And our guys were able to do it. We made him work hard for his points tonight, and that was critical."

Holiday led the Sixers with 18 points, while Andre Iguodala, who again did a stellar job on Paul Pierce (seven points, five turnovers), finished with 13 points, seven rebounds and six assists. Turner had 10 points, six rebounds and five turnovers.

"I think we saw the same type of game last game and we spoke on our day off and everything and we just all pulled together and believed we could win the game, and that's what really happened," Turner said.

In Saturday's Game 1 collapse, in which they led by as many as 13 before falling, 92-91, the Sixers looked like a young team losing to one that really just knew how to win.

Game 2 was different.

"We've just got to take it one game at a time," Pierce said. "It is what it is, I can't change it. We got our work cut out for us. They took the homecourt advantage now. We've got to try to find a way to get one or two wins in Philly."

The Celtics offense was especially dreadful during the 12 minutes of the third quarter, as they missed 13 of 17 shots, gave the ball away seven times and got beat on the boards, 15-10. It was a far cry from the third quarter of the series-opening game when Boston did the bulk of its damage during a 21-4 run.

Iguodala and Elton Brand combined to score 13 of the team's 21 points in the third, both capitalizing on midrange jumpers.

This one, however, was all about the defense. After getting torched by the ageless Garnett in Game 1, the Sixers and Lavoy Allen did a great job of taking him out of the game. Garnett was constantly facing double-teams as the Sixers decided to take their chances on letting Brandon Bass attempt long jumpers. It worked well for them as Bass missed 10 of his team-high 15 shots.

"I think we play some of our best basketball on the road," Collins said. "We had to win on the road to get into the playoffs. I think we have a comfort level now."

Another part of the maturing process.

"We think 2 nights ago we definitely gave one away," Lavoy Allen said. "There were a lot of things we didn't do. Now we're able to take the momentum going back home and continue to compete against these guys and play them tough."

Contact Bob Cooney at cooneyb@phillynews.com or on Twitter @BobCooney76.

Read the Daily News' Sixers blog at www.philly.com/Sixerville