Celts sign Marbury in time to play Friday he Boston Celtics signed Stephon Marbury Friday after the guard cleared waivers, and the club hoped to have theNew York Knicks castoff in uniform for Friday night's game against the Indiana Pacers. What role will Stephon Marbury play for the Celtics? Starter in backcourt Major contributor off bench Minor contributor off bench "We are very excited to have a player of Stephon's caliber joining our team," Celtics general manager Danny Ainge said in a statment."Our entire organization is confident in the belief that Stephon can play an important role in helping us to win another championship." Marbury, a former All-Star guard who alienated Knicks management, teammates and fans, was signed after having his physical at the Celtics' suburbanpractice facility early Friday. He agreed to a buyout of his $20.8 million contract and was waived by New York on Tuesday. The Celtics were expected to sign him for a pro-rated share ofthe veteran's $1.3 million minimum. Marbury, who turned 32 last week, hasn't played a regular-season game in more than a year. "I believe all systems are go and we will have Stephon on the roster later today," Celtics owner Wyc Grousbeck said in an e-mail to The AssociatedPress about an hour after Marbury cleared waivers. Marbury could be seen from the public area of the workout facility wearing a white, long-sleeved T-shirt and sweatpants, jumping up and down as he took thepractice court, smiling and chest-bumping with several people wearing Celtics gear. After a few minutes, the automatic shades were lowered. Marbury is expected to back up Rajon Rondo at point guard, a role Sam Cassell served when the Celtics won their 17th NBA title last season. Eddie House, who is more of a shooter, has been forced into the role this year; Cassell didnot play in a game for Boston this year before he was traded to the Sacramento Kings andreleased last week. Marbury took a long leave of absence from the Knicks when his father died in December 2007, then had season-ending ankle surgery and has not played sinceJan. 11, 2008. He returned to the Knicks in training camp, but when the sides tried to negotiate a buyout early in the season, Marbury at first refused to surrender anymore than $1 million of his $20.8 million salary and the team told him to stay home until a buyout could be completed. Even before the final breakdown, Marbury was at the center of controversy during his five years in New York, from feuding with coaches to skippinggames.