The Bruins improved to 18-13-0 with a win on the first stop of their three-game road trip.
With David Pastrnak back in the lineup, Sturm mixed up his bottom six to start, plunking his high-flying right wing on a new-look third line with Fraser Minten in the middle and Marat Khusnutdinov on the left side.
That moved bumped wingers Kastelic and Tanner Jeannot to the fourth line between Sean Kuraly.
The first 20 minutes, however, were all about the goalies, with Joel Hofer and Jeremy Swayman trading big save after big save.
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Swayman was tested early — as in 14 seconds early.
The Blues works the puck into Boston’s end of the opening face-off with Brayden Schenn dishing to Mathieu Joseph, who dumped one on Swayman, who was up for it.
The Bruins answered with a threat of their own with Viktor Arvidsson landing a ripper on Hofer from between the dots off a slick pass from Pavel Zacha.
A pinch-in by Nikita Zadorov proved costly when the Blues were able to send Nick Bjugstad in on a partial breakaway where Zacha was forced to slash him to prevent a quality bid.
St. Louis cashed in on the ensuing power play when Robert Thomas slammed a half-slapper past Swayman to cap a give-and-go with Pavel Buchnevich.
With Casey Mittelstadt and Logan Mailloux off with matching roughing minors, the Blues earned a 4-on-3 power play when Hampus Lindholm took down Thomas at the Blues blue line.
The Bruins were tighter on the kill, squashing it with Swayman (24 saves) standing tall.
The Bruins earned a power-play with just four seconds left in the period when Bjugstad got the stick up high on Morgan Geekie.
The Bruins weren’t able to capitalize on the power play though they generated a few decent chances, none better than Geekie’s scorching double doinker (off the crossbar and post) that Hofer never saw.
Still, the man advantage bolstered the Bruins, who dominated territorially, outshooting and outscoring the Blues to take a 2-1 lead after 40 minutes.
It could have been worse for the hosts if not for the play of Hofer, who came up with several dandies despite being under siege for most of the period.
Shortly after the Blues tried to rile up the crowd using a hype video staring St. Louis native and Celtics star Jayson Tatum (that’s dirty pool!), the Bruins struck for a pair of goals.
Following a traffic jam in front of Hofer that included bids by Pastrnak and Khusnutdinov, the puck squirted to Minten, who slammed it into the open net for his fifth goal of the season and second in two games.
Not long after Victor Soderstrom, playing in his third game as a Bruin, tossed one from the blue line that Kuraly redirect past Hofer to snap a 15-game goal scoring drought.
Jeannot picked up the secondary assist on the goal after inviting a hit along the wall to clear space to make the dish to Soderstrom.
Jim McBride can be reached at james.mcbride@globe.com. Follow him @globejimmcbride.
