Celtics forwards Paul Pierce, left, and Kevin Garnett turn back Lakers guard Kobe Bryant during Game Four of the NBA Finals. The Celtics defeated the Lakers, 97-91.

MCT / Michael Goulding

LOS ANGELES — One came from the Nets, another from the Heat and a third from the Clippers.

The two most important additions to the Boston Celtics came from the Super Sonics and the Timberwolves. A sixth came out of retirement halfway through the season.

The half-dozen new faces all gathered in Boston to feel the buzz created by such a dramatic overhaul of the Celtics’ roster. Each has played a key role, whether it’s leading men such as Kevin Garnett and Ray Allen or valued supporting actors James Posey and Eddie House.

Tonight, the 2007-08 Celtics may take the stage for the final time. The Celts are where they all dreamed of being — one game away from a chance at a championship. That was the goal over the summer, when Danny Ainge was pulling off monster trades and then sprinkling the rest of his roster with key additions.

Boston holds a commanding 3-1 lead over the Los Angeles Lakers. They take no solace in the fact that no team has ever climbed out of a 3-1 hole and won the NBA championship. They’d clearly like to close out Kobe Bryant and his mates tonight, even if they’d miss the wild celebration sure to uncork 3,000 miles away in New England.

“When you’re trying to achieve something, at least through my experience, it’s never easy, especially when it’s something that everybody wants and it’s something that you’ve been chasing for so long,” Garnett said. “Now this is it.”

Getting to this point was not easy. While the Celtics rolled to an NBA-best 66 regular-season wins, they did so more with hard work and defense than the flash-and-dash offense most basketball powers like to employ. The playoffs have been a major challenge. First came an unexpected seven-game series with Atlanta. Then another seven-gamer against LeBron James and the Cavaliers.

An expected battle royal with the Pistons ensued in the Eastern finals, although the Celts grabbed two sweet road wins and closed out the series in six games in Detroit. Now, surprisingly, the Celtics can knock out the Lakers in five in front of the Hollywood stars at the Staples Center.

Before a light practice yesterday, Garnett spoke about how the team came together off the court quickly. Sacrifice was the key word as Garnett and Allen joined Paul Pierce to form the best threesome in the NBA.

“The three of us have a respect for each other that we don’t really speak about, but we know that it’s there,” Garnett said. “We have a lot of dialogue about a lot of different things that half the time has nothing to do with the game, but it says a lot about who they are as individuals. And you know, we get real direct with each other and in certain situations you see the true sides come out of everybody, and it’s OK.”

When Garnett was introduced as a Celtic back on July 31, Allen and Pierce joined him at a news conference that anointed the new teammates and told the rest of the NBA that the Celtics were back. The team’s media guide was emblazoned with a headline that screams `Think Big.’

“I think since day one we’ve grown even tighter,” Garnett said. “I’ve always said through heavy debating and different opinions on issues (it) brings you closer because you obviously get to know that person in depth. And the three of us have figured it out and made it work. To be associated with those two and to be forever linked with those two is a blessing, and just for myself, it just makes me proud to be their teammate and more than that, but to be their personal friend, and I’m grateful.”

Coach Doc Rivers has orchestrated the mix of new faces with Celtics veterans, the old and the young. He says the entire group is hard-working and conscientious, always looking ahead to the ultimate goal.

“I think each guy leads in their own separate way. They’re all different. You know, it’s a team full of guys that kind of lead on our team,” Rivers said. “Kevin, with his intensity and with his focus, you know, and Ray is the talker of the group. He likes grabbing guys to the side, and you can call him the mentor of the group with a lot of the young guys. He enjoys that role. He does it. The young guys actually listen sometimes.”

The keys to any championship team often take years to develop. It’s taken this team one. Garnett and Allen, along with Posey, House, Sam Cassell and P.J. Brown, learned those valuable lessons before they came to the Celtics.

After he hit several key second-half shots in the Celtics’ remarkable Game Four comeback from 24 points down, House spoke about the resiliency of a team that didn’t require any time to quickly come together as a formidable unit.

“We haven’t given up all year. We’ve fought hard in every game, and that really showed tonight,” House said. “We like playing with each other and being in the foxhole with these guys. We compete hard at practices. That carries over to a night like tonight. We’re tough.”

With one more victory, they’re also going to be champions.

kmcnamar@projo.com