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Joe Mazzulla is no longer the interim coach of the Boston Celtics. He has officially replaced Ime Udoka as the head coach, the team announced on Thursday.

Boston named Mazzulla the interim coach in late September, just before the beginning of training camp, after suspending Udoka for one year for a "volume of violations," as team owner Wyc Grousbeck put it, including an inappropriate relationship with a woman who works for the Celtics. With the 34-year-old Mazzulla at the helm, Boston has gone 42-17 this season, the best record in the league, with the No. 3 offense and No. 4 defense.

Under Mazzulla, Jayson Tatum has become an MVP candidate, the Celtics have dramatically increased their 3-point rate and their offense has taken a step forward. Boston won 18 of its first 22 games, all of them without center Robert Williams III, it has won 16 of its last 21 games heading into the All-Star break, most of them without guard Marcus Smart

The Celtics have weathered injuries to Jaylen Brown and Al Horford, too. Some of this is a testament to the front office, which acquired Sixth Man of the Year candidate Malcolm Brogdon in the offseason and picked up stretch big Mike Muscala before last week's trade deadline. Some of the credit, though, must also go to Mazzulla, who has presided over a remarkably steady team. Boston has had the occasional stretch of cold shooting, but it has not lost more than three consecutive games. 

"As he has shown, Joe is a very talented coach and leader," team president Brad Stevens said in a statement. "He has a unique ability to galvanize a room around a mission. We are thankful for the work he has done to help get us to this point, and excited that he has agreed to lead us into the future."

The Celtics also announced that Mazzulla has signed a contract extension. 

Mazzulla and his staff will coach Team Giannis in Sunday's All-Star Game in Salt Lake City.