Celtics Coach Mazzulla Shoves Assistant Cassell

Heated exchange leads to ejection of Boston head coach during game.

Jan. 28, 2026 at 10:47pm

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Boston Celtics head coach Joe Mazzulla was ejected from a game after shoving assistant coach Sam Cassell during a heated sideline exchange. The incident occurred after Mazzulla received a technical foul from the officials.

Why it matters

Tensions between coaches on the sideline are rare but can be disruptive to a team's performance and chemistry. The Celtics are one of the top teams in the NBA this season, so this incident raises questions about the state of the coaching staff's relationship and ability to lead the team effectively.

The details

Video footage shows Mazzulla forcefully pushing Cassell after the two exchanged words following the technical foul call. Referees quickly intervened and ejected Mazzulla from the game. Cassell remained on the sideline as the Celtics went on to win the game.

  • The incident occurred during the 3rd quarter of the Celtics' game on January 29, 2026.

The players

Joe Mazzulla

The head coach of the Boston Celtics, in his third season leading the team.

Sam Cassell

An assistant coach for the Boston Celtics, a former NBA player, and respected veteran coach.

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What they’re saying

“Emotions got the better of me in the heat of the moment. I let my frustration boil over and that's not acceptable. I'll learn from this experience.”

— Joe Mazzulla, Head Coach, Boston Celtics (Celtics.com)

What’s next

The Celtics organization is expected to review the incident and determine if any disciplinary action will be taken against Mazzulla.

The takeaway

While heated exchanges between coaches are rare, this incident highlights the intense pressure and emotions involved in leading a top NBA team. The Celtics will need to quickly resolve any internal issues to maintain their focus and success this season.