Zadorov made it 2-0 at 13:49. After a scramble in front of the Vegas net, the puck trickled out toward Zadorov, who scored with a one-timer from just above the left face-off circle past a sprawling Samsonov.
Stone cut it to 2-1 on the power play at 15:09, redirecting Theodore’s point shot.
Morgan Geekie pushed the lead to 3-1 at 15:07 of the second period. After Samsonov misplayed the puck behind his net, Pastrnak fed Geekie from behind the goal line for a one-timer in the left circle.
Pastrnak has 26 points (11 goals, 15 assists) during his streak, which is tied for the longest of his career (2019-20).
Zach Whitecloud pulled Vegas within 3-2 at 19:26 when his slap shot from the point trickled through Swayman’s legs.
“I liked our game,” Golden Knights coach Bruce Cassidy said. “Our transition was good. Between the blue lines we managed pucks and got through there with speed at times. I thought we had the puck in their end for about 18 minutes in the second period and that goal from Whitecloud really helped. We need a break and we got it. We took care of business in the third.”
Pavel Dorofeyev tied it 3-3 at 4:54 of the third. He scored on a wrist shot from the bottom of the right circle off Theodore’s pass across the slot.
Dorofeyev had a goal overturned at 18:19 after the Bruins challenged for goaltender interference.
“They pushed and we sat back a little bit,” said Marchand, the Boston captain. “We knew they would be better in the second and third and they were. We got caught sitting back a little bit, and a team like that will make you pay.”
NOTES: Vegas forward Victor Olofsson left the game early in the first period with an upper-body injury after getting hit in the chest or throat area with a shot. There was no update. … Eichel has 50 assists for the second time in his 10 NHL seasons. ... The Golden Knights came back in the third period to win for the seventh time this season. … Marchand scored his 20th goal of the season, reaching the milestone for the 14th season to tie Patrice Bergeron for the second most in Bruins history, behind Johnny Bucyk (16). Marchand also has 12 straight seasons with at least 20 goals.