The Northeast Division leaders remained unbeaten in regulation and opened the season by earning points in five straight games for the first time since 1990-91.
Anton Khudobin stopped 29 shots in his first start of the season for the Bruins.
Krejci's winner came after Horton rang the post. Rookie defenceman Dougie Hamilton's cross-ice pass found Krejci in the left circle and he snapped the puck past Ward for his first goal of the season.
COYOTES 4, PREDATORS 0
GLENDALE, Ariz. (AP) — Chad Johnson earned his first NHL shutout in his Phoenix debut and the Coyotes beat Nashville.
Johnson, called up from Portland of the AHL last week after Mike Smith was hurt, had 22 saves in a game dominated defensively by a Coyotes team that entered the night allowing an NHL-high 20 goals in five games.
The Predators were shut out for the second time in three games and have scored just 10 times in six games this season.
BLUE JACKETS 2, STARS 1
It was the Blue Jackets' first victory since opening night in Nashville in a shootout. They had been outscored 16-6 since while mustering just a point in a shootout loss to Detroit in the home opener a week ago.
Derek Dorsett also scored for the Blue Jackets.