After appearing to turn a corner with back-to-back shutouts this past weekend, the Boston Bruins returned to old habits on Tuesday.

Allowing three power-play goals in a 4-0 loss to the Toronto Maple Leafs ended the Bruins’ chances for their first three-game win streak this season. But they will look to start a new streak when the Calgary Flames pay a Thursday visit to Boston.

Tuesday marked Boston’s fourth time surrendering three goals on the man advantage in a 10-game span and its third time being shut out. The power play was 0-for-6 against Anthony Stolarz and the Maple Leafs, who had lost the previous eight regular-season meetings between the teams.

“The players that get the privilege of either being on the penalty kill or the power play, along with us coaches, need to be better with our plan and … in our execution,” Bruins coach Jim Montgomery said.

David Pastrnak (six goals, 11 points) took four shots on goal and drew three penalties in 22:18 in Toronto after being benched for the third period of a 2-0 Sunday win over the Seattle Kraken. He played the most of any Bruins forward.

It was some evidence of a solid 5-on-5 game, but special teams — the 29th-ranked power play (13.3 percent) and 20th-ranked penalty kill (76.2) in the NHL — need to be better.

“Honestly, it was a tough loss, but I feel like we’ve been right there for most of the game and the special teams obviously hurt us,” Pastrnak said.

Montgomery is seeing overall improvement, though.

“Our habits and details are growing,” Montgomery said. “You don’t like losing 4-0, but they got three power-play goals. We look at our 5-on-5 game, we don’t think we’re giving up that much. … We still don’t get the O-zone time we love to have, but that’s a work in progress.”

The Bruins lost defenseman Andrew Peeke (upper-body injury) following a hit by Toronto’s Max Pacioretty in Tuesday’s first period. There is no update regarding his status.

The Flames have won two of three since a four-game skid and arrive in Boston for the second game of a three-game Atlantic Division road trip after downing the Montreal Canadiens 3-2 in overtime on Tuesday.

The star of the night was 21-year-old Matt Coronato, who scored twice — first with 2:46 left in regulation and then seven seconds into overtime — in only his third game since being promoted back to Calgary from the American Hockey League.

The Harvard product has four goals in eight NHL games this season.

“The kid can shoot it, a couple big ones,” linemate Blake Coleman said of Coronato. “He’s really talented and he’s a hardworking kid and he’s humble, he brings a lot to the table.”

Connor Zary, who had recently been dropped to the fourth line, scored Calgary’s first goal. Fellow 23-year-old Dustin Wolf made 15 of his 21 saves in the first period to keep the game scoreless.

Though the standout performances from youngsters in the Flames lineup were encouraging, coach Ryan Huska, like Montgomery, has a team with questions to answer in specialty situations.

Calgary’s power play ranks 23rd in the NHL (15.8), but only one of its six goals have come over the last eight games. The penalty kill has been the worst of the two units at 27th (72.1).

“Five-on-five, there’s some things that are happening for us,” Huska said. “I like the effort we have from just about everybody in our lineup, (but) we just want to try and get the other side of the game going as well.”