WALTHAM, Mass. – In front of a slew of TV cameras and newspaper reporters, the Celtics introduced their newest acquisition, four-time All-Star power forward Rasheed Wallace at a news conference in Waltham on Thursday.

Wallace arrived with his wife, Fatima, their four children, Boston's Big Three, Celtics president of basketball operations Danny Ainge and coach Doc Rivers.

Wallace, 6-foot-11, who was one of this year's most coveted free agents, signed a reported three-year contract with the Celtics on Wednesday. His decision came less than a week after a three-hour meeting with Ainge, Celtics' owner Wyc Grousbeck, Rivers and the Big Three.

Wallace said he knew Ainge, Rivers and Grousbeck would be at the meeting, but he was totally surprised when he walked into the conference room and saw Kevin Garnett, Paul Pierce and Ray Allen there, too.

He said Boston's Big Three being there meant a lot to him and showed him how much they wanted him to play in Boston.

"We wanted him and his family to know how serious we were about winning and how serious we were about having him be a part of this franchise and this family," Allen said.

"They opened their arms for me and my family to be a part of their Boston Celtics family," Wallace said.

That, along with the fact that Wallace believes the Celtics give him the best chance to win another NBA title were the major factors that persuaded Wallace to pick Boston instead of San Antonio, Orlando, Cleveland or Dallas, he said.

"I felt as though it was a good fit," Wallace said. "I think one of the main things that the guys up here do is play defense. They have been in the top one and two in defensive categories over the last two years, so that's saying a lot about their defense right there.

"That's saying a lot about them and their whole defensive scheme. The bottom line is just to win, so that pretty much persuaded me to come over here. They are a pretty good group of guys."

The Celtics believe that Wallace will be a big boost in their quest of recapturing the NBA championship they won in 2008 and Ainge said the Celtics were "ecstatic" to add a player as talented as Wallace.

The signing of Wallace has been a long time coming. Rivers said the Celtics began talking about recruiting him as soon as last season ended.

"Right when the season ended you looked at the free-agent list and there was one name that popped out right away, and it was Rasheed's," Rivers said. "We didn't know if we could get him or not, but we knew that's who we wanted. It was clear to our team with who he was and how he plays that he was a perfect fit for us."

"I'm excited," said Garnett, who also said his rehabilitation was ahead of schedule. "I'm really excited about the year. This is not only a key addition but a major addition to our team. It almost feels like AAU basketball all over again. The versatility that Sheed brings —,I'm just happy that his family has joined our family and we're going to make the best of this. I am totally excited."

Wallace brings length, passion, physicality, experience and versatility to Boston's lineup.

"I just think he's a great addition," said Pierce. "We had depth issues last year because of injuries, but just bringing in a guy like Rasheed with his experience, and the things he does on the court with what we do, like I said, I think it fits in right like a piece in a puzzle. I think it's going to be an exciting year. Everybody knows what we are all about — winning a championship."

The defending NBA champion Los Angels Lakers got better by signing Ron Artest. The defending Eastern Conference champion Orlando Magic improved by adding Vince Carter. And the always-dangerous Cleveland Cavaliers got better by adding Shaquille O'Neal. Ainge and Rivers said it was important for the Celtics to sign a veteran marquee player if they were going to have a chance to compete with those teams.

"I did think we needed to add some pieces and hopefully we are not done," Rivers said.

The Celtics are also hoping to sign Grant Hill.

"I think we did have to do something," Pierce said. "You look around the whole league and you look at the teams at the bottom and the teams at the top. It's like all the teams at the top got better, and for us not to do anything, we would lose this race, so it was a must for us to go out and get Rasheed."

Wallace is expected to back up Garnett at the power-forward position and Kendrick Perkins at the center spot, which will be an adjustment. Wallace has started 943 of his 1,009 regular-season games.

But Wallace said he was willing to do whatever Rivers asked him to do and if that means coming off the bench, that's what he'll do. He said he would rather score one point and have the Celtics win than score 100 points in a loss.

Along with an array of post moves that he developed over his 14-year career, Wallace is also deadly from long range, which opens things up for his teammates.

Wallace has averaged 15 points and 6.9 rebounds with 1.3 blocks while playing almost 34 minutes in his 14 seasons.

"He gives us more length," Rivers said. "He gives us more versatility . . . Offensively I like him for [Rajon] Rondo more than anybody because I just think when teams try to play off of Rondo, usually what they would do is play off of Rondo and use Perk's guy, but it's tough to do that when that guy is standing behind the 3-point line, so he does give us a bunch of openings."

Wallace averaged 12 points and 7.4 rebounds for Detroit last season.

"I don't think there's any secret of the enthusiasm and the excitement of our franchise, the ownership, management, coaches, fans and of course teammates that were here trying to persuade Rasheed that this was the place for him to be," Ainge said. "We're very excited to have him. We think he's a great fit in our community. He's a great fit on the court.

"His skills, his personality in the locker room, his intelligence, his experience [are all great]…. He's one of the great defensive communicators on the court, and that's huge. Between him and KG and Perk, having the back-line guys with their experience, he'll fit right in with our guys."

roblee@projo.com