Or he can use his second line with center Ryan O'Reilly, who, like Bergeron, is a finalist for the Selke Trophy as the top defensive forward in the NHL.
St. Louis' fourth line might have also been an option before center Oskar Sundqvist was suspended for one game Thursday for boarding Boston defenseman Matt Grzelcyk in Game 2.
"The lines that are out there against them, whoever it is, they're doing a good job of backchecking and tracking and being tight on them," Berube said. "It's a very good line. It's hard to handle them, for sure. They do a lot of things well. So far, it's been pretty good, but we've got to continue to do that. It's a tough line to defend."
The Toronto Maple Leafs, Columbus Blue Jackets and Carolina Hurricanes can attest to that after struggling to contain Marchand, Bergeron and Pastrnak in the first three rounds of the Stanley Cup Playoffs.
Marchand is second in the playoffs with 19 points (eight goals, 11 assists), one behind San Jose Sharks center Logan Couture. Pastrnak is tied for fourth with 16 points (seven goals, nine assists), and Bergeron has 13 points (eight goals, five assists).
The Blues suffocated them for much of Game 2 before Bergeron (2:38 left in the third period), Marchand (51 seconds remaining) and Pastrnak (46 seconds left) each had an open scoring chance late that goalie Jordan Binnington saved.
"I think we just continue to play tight against them as a full five-man unit, and [Binnington] is making the stops when he needs to," Parayko said. "Us D-men, we are trying to play tight on them, not allowing them to kind of come into our zone and just generate opportunities, and that's the main thing.