BOSTON — The first goal of the game was a reminder of Mason Lohrei’s potential. His elite vision and terrific skill.

The last goal of the game — Mitch Marner’s overtime strike that gave Toronto a 5-4 win over the Bruins — was a reminder that for all his potential, Lohrei is still a 24-year-old figuring out how to play in the NHL.

The Bruins are getting the full spectrum of the Mason Lohrei experience in 2024-25. On Tuesday, he was on the ice for five goals — two for the Bruins that he assisted on and three for the Leafs.

When the Bruins are at full strength, Lohrei’s evolution is a little more natural. But with Hampus Lindholm done for the season and Charlie McAvoy out indefinitely, Boston has been forced to give Lohrei more minutes and in more crucial spots and hope that the birdies outweigh the bogeys.

“It’s definitely an opportunity. I want to do the best with the extra time I’m getting with those guys being out,” Lohrei said.

Just 29 seconds into Tuesday’s game, he surveyed the ice and saw David Pastrnak with a step on the Toronto defense. He threaded a perfect pass to the Bruins forward, who scored easily on the breakaway.

“That was a world-class pass,” Pastrnak said. “I was surprised. It landed right on my stick.”

But in overtime, Lohrei was caught leaning the wrong way as the Leafs tried to clear the zone. It was the second time in the game he’d made the wrong decision whether to be aggressive or cautious.

The first one led to a penalty in the second period. On an attempted clear, Lohrei started backpedaling but then changed his mind and shifted forward, attempting to keep the puck in.

He was late and ended up being called for cross-checking Marner leaving the zone.

Only he knows if that was in his mind in overtime when he was aggressive right away trying to keep the puck in.

But this time he should have retreated against the Maple Leafs’ top two forwards. With Pastrnak and Pavel Zacha stuck deep in the zone, Lohrei leaned, trying to reach and redirect the puck back into the zone. That left him with no momentum to get back when he wasn’t successful.

“Our defenseman was caught up a little in between there whether to move up or stay back. They pushed it by him,” Bruins interim coach Joe Sacco said.

Auston Matthews tapped a pass to Marner, who finished his breakaway as easily as Pastrnak did.

Sacco didn’t want to blame Lohrei.

“Three-on-three hockey has a couple of breakdowns here and there,” Sacco said. “Mason did a lot of great things tonight. Especially early on, he was ready to play.”

Lohrei is trying to stay even and keep his eye on his goals through the ups and downs.

“It’s tough. I know what kind of player I am, what kind of player I want to be,” he said. “I’m just trying every day. I want to be that guy who creates a lot and doesn’t give up anything. I’m just trying to continue to work at that. It’s all I can do.

“I’m just trying to keep my confidence and go out and make the next play,” he continued. “You can’t lose your confidence if something bad happens. It’s a game of mistakes, but I have to limit them.”

FREDERIC INJURED: In a development that could impact the trade deadline, Bruins forward Trent Frederic left Tuesday’s game against Toronto with an apparent leg injury.

Frederic skated off awkwardly after a collision with Jake McCabe in the offense corner, 4:11 into the second period.

He went to the bench and then the dressing room. There was no immediate update on his status.

Frederic’s absence could affect the Bruins’ trade deadline situation. Frederic is among the Boston players most likely to get moved.

He’s an unrestricted free agent at season’s end. Frederic could offer a contender a big physical presence with a history of making an offensive impact and could potentially benefit from a change of scenery in the midst of a down year