WALTHAM, Mass. — When Shaquille O’Neal was much, much younger and a good deal smaller, too, he chose as a role model one of the most successful big men in NBA history.

“When I came into the league, I wanted to compete with Bill Russell for titles,” O’Neal said Tuesday, with Russell’s 11 championship banners hanging above him at a news conference to mark his signing with the Boston Celtics. “That’s not going to happen, but I’d like to almost get half of what he got.”

With four titles and a Hall of Fame career already on his resume, newly christened “Big Shamrock” signed a two-year deal with the Celtics at veteran’s minimum, forgoing more lucrative offers to join the defending Eastern Conference champions for a run at another title or two.

A crossover celebrity who has appeared in feature films and his own TV show, O’Neal joked about his new nickname, his fear that his kids will develop a Boston accent and trying to beat new teammate Glen “Big Baby” Davis in a chowder-eating contest.

But he was serious when he talked about his legacy.

“Do I have the same hunger? Yes. If I didn’t, I wouldn’t be here,” O’Neal said. “I don’t like wasting my time. I don’t like wasting anybody’s time. At the end of the day, when I close the book, it’s all about winning.”

The news conference to introduce O’Neal, 38, wasn’t the usual type for a backup center who will be paid about $1.3 million a year. There were a dozen TV cameras, perhaps 50 reporters in all and a couple hundred beaming schoolchildren in the bleachers, taking a break from their basketball camp next door.

“To me this is a very exclusive event,” said O’Neal, who wore a gray pinstripe suit and a black bow tie. “It’s my last (introductory) press conference. I just wanted to be very, very sharp.”

The crowd was all there to see O’Neal the superstar, the former NBA MVP and four-time champion who is certain to enter the Hall of Fame in Springfield when he decides he’s had enough.

But the O’Neal the Celtics have signed is a much different player than the one who accumulated those credentials.

Now weighing in at 345 pounds – he was 294 at LSU – O’Neal averaged 12 points and 6.7 rebounds for the Cavaliers last season, when he was brought to Cleveland in the hopes that he would be the missing piece that would help LeBron James win his elusive NBA title. He also missed almost two months of the season after injuring his thumb against the Celtics.

“I told him there won’t be 30 minutes (for him) on this team; there will be 20-25,” Coach Doc Rivers said. “I asked him if that would be OK, because that’s the only way it’s going to work.”

And it was OK with O’Neal, who hit the free agent market seeking a two-year deal worth a reported $8 million to $10 million a season. The Celtics expressed an interest – though not at that price – and GM Danny Ainge moved on to pursue other options. As the summer wore on, though, O’Neal came around.

“When he was in his prime, he was considered one of the best who has ever played,” Ainge said. “Shaq coming to our team right now, our expectations won’t be that. We expect him to contribute to our team and play a role off our bench.”

But that can be a major contribution for a team that is without center Kendrick Perkins for at least half the season while he recovers from the knee injury sustained in Game 6 of the NBA finals. Backup Rasheed Wallace has said he will retire, though the Celtics could do something with his deal. Boston signed Jermaine O’Neal, another veteran, and then added Shaq. There won’t be a problem with playing time until Perkins returns.

“Shaq still can do things that no other big man can,” Rivers said. “You need size to win. We think we filled that void pretty well today.”

The Celtics won their NBA-record 17th title in 2008, then returned to the finals last year before losing to the Lakers in seven games. While the Miami Heat have rebuilt around Dwyane Wade, LeBron James and Chris Bosh, the Celtics have largely brought back the core of last season’s team, re-signing Paul Pierce and Ray Allen to keep them alongside Garnett and point guard Rajon Rondo.

“I realize I only have 730 days left in this game. I just wanted to be with a group of guys that like to win,” O’Neal said. “This was a good team with or without me. I don’t mind playing a role. I know where I am at this point in my career. It’s about coming to a team that is one or two pieces from a championship.”