Boston’s Garnet Hathaway, back left, wrestlers with Tampa Bay’s Pat Maroon, while Jakub Lauko of the Bruins, center right, battles with Ross Colton during the first period Saturday in Boston. Michael Dwyer/Associated Press

BOSTON — The Boston Bruins are winning so much that clinching their division didn’t merit any celebration. Captain Patrice Bergeron didn’t even realize it had happened.

Garnet Hathaway scored the tiebreaking goal late in the second period and the NHL-best Boston Bruins wrapped up first place in the Atlantic Division with their sixth straight victory, 2-1 over the Tampa Bay Lightning on Saturday.

The win was the Bruins’ 56th and moves them one behind the club record set in 1970-71. It also keeps them on pace to set the NHL record for victories in a regular season with 10 games left. The Detroit Red Wings won 62 games in 1995-96 and Tampa Bay matched it in 2018-19.

“I forgot because things were happening so quickly,” Bruins first-year coach Jim Montgomery said when asked what he told his team about winning the division. “We didn’t actually talk about the Atlantic Division, but it’s a tremendous feat with 10 games left.”

Patrice Bergeron added a power-play goal for the Bruins and Linus Ullmark made 26 saves, raising his record to 36-5-1.

“Last game, you mean?” Bergeron said when asked about winning the division. Informed it had happened Saturday, he said: “Oh really.”

Victor Hedman got a short-handed score for the Lightning, while Andrei Vasilevskiy stopped 32 shots. Tampa Bay has lost four straight.

“I thought we played physical. I thought we played the way we want to play,” Hedman said. “That’s kind of the mindset we went in with and talked (about) before the game. I’m proud of the guys the way we battled today.”

Hathaway, positioned in front of the net, batted the rebound of Matt Grzelcyk’s shot from the left point out of the air and into the net before Vasilevskiy could control it with 2:28 left in the second period.

Ullmark stopped Anthony Cirelli’s backhander on a partial breakaway with about seven minutes left.

With Lightning winger Pat Maroon in the penalty box after an unsportsmanlike conduct penalty for something he did on the bench, Bergeron was credited with his 27th goal when Brad Marchand’s pass hit his skate before caroming into the net off Hedman’s skate 6:46 into the opening period.

Hedman beat Ullmark with a slap shot from the top of the left circle just under three minutes later.

EARLY DUSTUPS

Maroon and Hathaway had to be separated before the opening puck drop. It didn’t matter, they dropped their gloves just nine seconds into the game. The scrum started when Tampa Bay center Ross Colton, who got a double minor for roughing, went after Boston center Jakub Lauko.

WELL DONE

The Bruins killed a 5-on-3 Tampa Bay power play midway through the second.

Tampa Bay was short-handed five times in the opening period but held the Bruins to one goal.

NOTES: Bruins forward A.J. Greer served a one-game suspension for crosschecking Montreal’s Mike Hoffman in the face in Thursday’s 4-2 victory over the Canadiens. … The Bruins came in with the league’s top penalty-killing unit (85.4%), while the Lightning owned the third-best power play (25.5%). … Boston forward David Pastrnak’s next goal will be the 290th of his career and move him ahead of Ken Hodge for eighth on the team’s all-time list.