BOSTON — Rasheed Wallace is joining Boston's Big Three as the Celtics try to recapture the NBA championship they won in 2008.

The four-time All-Star known for his shooting, rebounding and technical fouls signed Wednesday, the first day free agents were allowed to do so.

One of the most coveted players available, Wallace joins Kevin Garnett, Paul Pierce and Ray Allen as the veteran corps of a team that lost to Orlando in seven games in the Eastern Conference semifinals one year after winning its 17th NBA title.

Terms of the deal were not released. Wallace earned $13.68 million last season as he completed a five-year contract with Detroit.

Wallace can play the low post and has exceptional shooting range. He averaged 12 points per game for the Pistons last season, the 14th straight year in which he had averaged at least 10 points per game.

 Celtics general manager Danny Ainge said the team was "ecstatic" to add a player with Wallace's talent and championship experience. He won a title with Detroit in 2004.

With Boston, the 6-foot-11 Wallace figures to back up Garnett at power forward and Kendrick Perkins at center. The Celtics also could retain Glen Davis, a restricted free agent who filled in well when Garnett missed the playoffs with a knee injury. Garnett had surgery and is expected back for training camp.

Wallace has averaged 15 points and 6.9 rebounds with 1.3 blocks while playing almost 34 minutes per game in his 14 seasons. Now he must adjust to a backup role after starting 943 of his 1,009 regular-season games.

He also must try to keep his temper in check. He was suspended for Detroit's game at New Jersey on April 1 for picking up his 16th technical of the season the previous night.

But Ainge loves Wallace's productivity and his ability to draw big men away from the basket with his 3-point shot.

"We are ecstatic to be able to add a player the caliber of Rasheed Wallace to our team," Ainge said. "It is not every day that you can add a four-time All-Star and a player with championship experience."

The Celtics put a full-court press on Wallace in their bid to bring him to Boston. Last week, Ainge, coach Doc Rivers, owner Wyc Grousbeck, Garnett, Pierce and Allen visited him at his home in the Detroit area. His agent, Bill Strickland, said during the weekend that Wallace had decided to join the Celtics.

The Celtics are also in the chase for Phoenix Suns free agent Grant Hill, but the Knicks appear to have the inside track.

"I think we tried to impress him and to show him what we had," Knicks president Donnie Walsh said after meeting with Hill. "I think we accomplished that."

Hill, who spent the last two seasons in Phoenix, is also mulling invitations from the Suns and the Celtics. The Knicks and the Suns can offer the most money and a full-time starting job. Boston can offer the best shot at a title but only a spot as a backup to  Pierce and Ray Allen, which could prove to be a deal-breaker.

Hill has a comfort level with the Suns' roster and with coach Alvin Gentry. But he also grew close to Knicks coach Mike D'Antoni during their one season together in Phoenix. No other teams are believed to be in the hunt, and the sense is that Hill could make a decision by the end of the week.

Signing Hill, a widely respected former All-Star, could help stabilize the Knicks' lineup and make them more attractive to young superstars. Hill is still a solid defender, scorer and playmaker who can play at small forward, shooting guard and, in a pinch, at point guard.

"He's the kind of guy we want," Walsh said.