In first two games of the Cup Final, Blues coach Craig Berube used Sundqvist's line at times against the Bruins' top line of Brad Marchand, Patrice Bergeron and David Pastrnak.
"[Sundqvist] has always been a very good defensive player, a penalty killer for us, a hard-working guy," Berube said. "But his offensive side has really come through this year. He scored quite a few goals during the regular season and he's gotten four in the playoffs here. … He's playing a real good 200-foot game and we've kind of used him in all different situations."
Before the suspension was announced, Berube declined to discuss how the Blues planned to replace Sundqvist.
With forward Robert Thomas' status for Game 3 unknown after he missed Game 2 with an unspecified injury, Barbashev could shift to center and forward Zach Sanford could be put into the lineup. Sanford, who hasn't played since Game 3 of the Western Conference First Round against the Winnipeg Jets, has no points in three playoff games.
Another option for the Blues would be to use seven defensemen if Vince Dunn can play. He hasn't played since being struck in the mouth by the puck in Game 3 of the Western Conference Final against the San Jose Sharks. Berube said there is a chance Dunn will be available Saturday.
"We have so many guys who can step in and do the job and, obviously, it's tough losing key players like that, but we're confident," Blues center Ryan O'Reilly said. "We have a great group here and so many guys who are able to step in and make an impact."