Celtics newcomer guard Sam Cassell attended shoot around this morning. The two-time NBA champion got a warm welcome from his new teammates who even slapped his hand as they ran up the court. Celtics coach Doc Rivers shot down a report from TNT that Cassell would play tomorrow at Memphis and said he wasn’t certain when the debut would take place. Rivers is also uncertain if Celtics newcomer P.J. Brown will make his debut tonight against Chicago.