The Boston Bruins have fired coach Jim Montgomery after stumbling to a losing record in their first 20 games, the team announced Tuesday.

Associate coach Joe Sacco was elevated to interim head coach. The Bruins are off to an 8-9-3 start (.475 points percentage) and outside of a playoff seed in the Eastern Conference.

General manager Don Sweeney called the move “a difficult decision.”

“Jim Montgomery is a very good NHL coach and an even better person. He has made a positive impact throughout the Bruins organization, and I am both grateful and appreciative of the opportunity to work with him and learn from him,” Sweeney said in a statement.

Sacco was previously coach of the Colorado Avalanche from 2009 to 2013 and has been a part of the Boston coaching staff since 2014. The 55-year-old had a 13-year NHL playing career with five teams from 1990 to 2003.

“Our team’s inconsistency and performance in the first 20 games of the 2024-25 season has been concerning and below how the Bruins want to reward our fans. I believe Joe Sacco has the coaching experience to bring the players and the team back to focusing on the consistent effort the NHL requires to have success,” Sweeney said. “We will continue to work to make the necessary adjustments to meet the standard and performance our supportive fans expect.”

Montgomery, 55, had a 120-41-23 record (.715 points percentage) in three seasons with the Bruins, making the playoffs twice. Both trips to the postseason ended at the hands of the Florida Panthers. Boston was stunned in a seven-game, first-round upset in 2023 after having the most successful regular season in NHL history (135 points), and again earlier this year when it lost to Florida in the second round after eliminating the Maple Leafs in seven games.

Montgomery won the Jack Adams Award as NHL coach of the year in 2022-23. He previously coached the Dallas Stars for two seasons (2018-20), amassing a record of 60-43-10.

As Montgomery chronicled in his 2023 NHL Awards speech, his success in Boston came after he turned his personal life around. “Three and a half years ago, the Dallas Stars terminated my contract because of my struggles with alcohol,” he said. “And I had to change my actions and behaviors.”

Despite Sweeney saying the sides were discussing an extension during training camp, Montgomery didn’t have a contract beyond the 2024-25 season.

The Bruins have been one of the NHL’s most notable disappointments this season. They’re 31st in team offense (2.40 goals per game) and 28th in defense (3.45 goals against per game).

Previously dependable aspects of the team have malfunctioned, in particular the goaltending. The team traded former Vezina winner Linus Ullmark to the Ottawa Senators for goalie Joonas Korpisalo. The Ullmark deal broke up the best goalie tandem in the NHL with 26-year-old Jeremy Swayman, who missed training camp during a bitter negotiation before signing an eight-year contract that will pay him $66 million.

Swayman has a 5-7-2 record with an .884 save percentage and a 3.47 goals-against average. After the Bruins lost to the Columbus Blue Jackets 5-1 on Monday, Montgomery said missing training camp wasn’t advantageous.

“I don’t think missing training camp helps anyone,” Montgomery said. “That’s why you have training camps.”

Montgomery has been seen having animated discussions with captain Brad Marchand on the Boston bench multiple times this season. He also benched leading goal scorer David Pastrnak in a game earlier this month.

Montgomery’s firing is the first coaching change of the 2024-25 season. Sacco is the fourth head coach under Sweeney since the GM took over in 2015.

“I’m supportive of Don’s decision to address our current play and performance,” team president Cam Neely said in a statement. “Joe Sacco has a wealth of experience and knowledge of our roster and can help lead our team in the right direction. He has a strong understanding of our standards and expectations, and I trust he will do all he can to accomplish our organization’s goals this season.”