Cassell's debut with Green rust-colored

Sam Cassell, getting back into the flow in his Celtics debut, passes in front of Shavlik Randolph. (h. rumph jr./Associated Press)

PHILADELPHIA - When Sam Cassell's jumper sailed high above the rim late in the fourth quarter for an airball, it was safe to say he was a little rusty.

In his Celtics debut last night against the Sixers, Cassell was scoreless on 0-for-2 shooting and had 1 rebound, 1 assist, 4 fouls, and 2 turnovers, playing 5:24 of the 100-86 victory at Wachovia Center. It was his first action since Feb. 20, when he was still a Clipper.

Cassell, who averaged 12.8 points and 4.7 assists for Los Angeles this season, took the start in stride.

"I haven't played in 2 1/2 weeks," he said. "It's going to be all good. It ain't going to take long."

The 14-year NBA veteran, who was signed by Boston a week ago after being bought out by the Clippers, said he wasn't nervous in the least before the game. He relaxed during the day at the team hotel by watching the MTV show "Making The Band."

Cassell entered with Boston ahead, 38-34, with 7:07 left in the half. He replaced Tony Allen and joined Eddie House in the backcourt. The Philadelphia fans, renowned for being testy, welcomed the 38-year-old with boos.

He was replaced with 4:02 remaining in the half after picking up his third foul in just three minutes. He returned with Boston up, 98-79, with 2:19 left in the fourth quarter and played to the final buzzer.

"My wind is fine, just my timing is off," Cassell said. "I don't know the sets. I don't know where to go on the court."

Scalabrine bumped
When Celtics coach Doc Rivers told forward Brian Scalabrine he had something to talk about yesterday morning, Scalabrine had a hunch he probably wasn't going to be in uniform last night.

To make room on the 12-man active roster for Cassell, Rivers and executive director of basketball operations Danny Ainge decided to place Scalabrine on the inactive list.

Scalabrine joined center Scot Pollard (out for the season with an ankle injury) and rookie guard Gabe Pruitt on the inactive list.

"I knew already," said Scalabrine. "I'm not dumb. I'm not one of the high-end players."

Scalabrine is averaging 1.9 points and 1.5 rebounds in 10.4 minutes per game (41 games), and has a .317 field goal percentage. His field goal percentage is the lowest on the team, and only Pruitt is averaging fewer rebounds. The recent addition of forward-center P.J. Brown also took up a potential roster spot for Scalabrine.

"I can understand why I am being put on the list right now," Scalabrine said. "I don't think I've played as well as I could've played. But it's just an unfortunate situation. I was starting [when Kevin Garnett was out] and then I got hurt. I've come out of the rotation since.

"There are things I can improve on. I have to continue to try to do that."

In the meantime, the six-year veteran was told by Rivers to "always be ready," and keep working on his ball-handling for "timing" during games.

"I just want to continue to work and get better," Scalabrine said. "I'll always know that if anything happens in the NBA, I'll be ready if a guy goes down. I'll just schedule my workouts and be ready to go.

"It's a lot bigger than Brian Scalabrine, this whole thing. It's about winning a championship for the Boston Celtics. If Danny and Doc believe it's best for me to be on the list, then that's my role.

"As a competitive person, you want to fight and go out there and give yourself minutes. But on the other hand, you have to realize that we're in a situation where we are going for a championship and those guys are the ones that are helping us right now."

Rivers said Scalabrine's attitude was "fantastic," and that "for the most part" the entire team was that way.

"Those are the types of guys you need on your roster," Rivers said.

Latest developments
In two games since being reassigned to the Utah of the D-League, Pruitt has averaged 19 points, 7 assists, 3.5 steals, and 2 turnovers in 37 minutes . . . Rivers will be a candidate for NBA Coach of the Year, but he thinks Philadelphia's Mo Cheeks deserves consideration because his team is overachieving and in playoff contention. "Mo has done a better job than anybody in the league," Rivers said.

Marc J. Spears can be reached at mspears@globe.com.