BOSTON — Anders Bjork’s pass deflected off a defender’s rear end and Sean Kuraly’s leg to break a tie late in the first period, and help the Boston Bruins win their fourth straight game, 4-1 over the Pittsburgh Penguins on Thursday night.

“It was an ugly one, so I didn’t even know if I wanted to take credit for it,” Bjork said. “You saw that ugly one go in, but our line was battling and that’s kind of what happens when you play the right way.”

Patrice Bergeron had two goals and Chris Wagner also scored for Boston. Jaroslav Halak stopped 16 shots for the Bruins’ second victory over Pittsburgh in three days. The goals were Bergeron’s fourth and fifth of the season and the first for Kuraly and Wagner.

“We knew the floodgates were going to open eventually,” Wagner said.

Cody Ceci scored his first goal and Tristan Jarry had 16 saves for the Penguins, who arrived in Boston with a four-game winning streak but have now lost two in a row.

“They’re fast, they’re hungry, they win every battle in the corner. We need to look into the mirror,” Penguins forward Evgeni Malkin said. “It’s not a pretty game right now. We need to play simple and just work, work, work.”

Wagner gave the Bruins the lead early in the game, but Ceci tied it with five minutes left in the first period.

With about a minute to go in the first, Bjork made a nice move to get past a stickless defender at the point, then flipped the puck toward the net. It bounced off of Teddy Blueger’s bottom and through another defender’s legs before deflecting off Kuraly’s leg into the net.

Bergeron made it 3-1 in the second, getting the rebound after his first attempt hit a skate and sliding the puck over to his backhand, then past Jarry. The Bruins’ captain added another on the power play early in the third.

INJURY

PENGUINS: Pittsburgh played without one of its best defensemen, Brian Dumoulin of Biddeford, because of a lower-body injury.

Dumoulin, a steadying force next to Kris Letang on the top pair and a trusted voice in the locker room, left Tuesday’s overtime loss to the Bruins at the end of the second period and did not return.

Dumoulin is second on the Penguins in ice time at 19:23 per game, behind only Letang.

SHAKEUP

It was the first game for the Penguins since general manager Jim Rutherford abruptly stepped down on Wednesday. Rutherford, who built the teams that won the Stanley Cup in 2016 and ’17, cited personal reasons and declined to get into specifics with anyone, including his stars.

“I want to say thank you to Jim, for sure,” Malkin said. “He won two Cups, it’s amazing. He’s a great person, great GM. It’s a surprise.”

PRAYERS UP

Before the game, Bruins forward Brad Marchand hung a jersey behind the bench for A.J. Quetta, a senior at Bishop Feehan High School in Attleboro who was in critical condition after crashing headfirst into the boards in a game this week.

“We’re all praying for A.J.,” Wagner said. “Makes us think how fragile life is.”

The Bruins, their owners and their charitable foundation have pledged at least $100,000 toward his recovery.