But the Stars rallied with two goals before the end of the period, Jason Dickinson scoring at 11:23 and Jason Spezza scoring on the power play at 19:08 with Tyler Bozak serving an interference penalty.
"A big goal by [Tarasenko, but] we didn't get to our game enough," Perron said. "We have to be a little bit more physical and into them. That was tough to obviously get scored on [during] the [Bozak] call. At the end of the day, we have to play better at the end of the second period. They were the better team. We have to do like we did in the third period."
Dallas scored twice in the second, which dissolved into a mess at the horn. Blues goalie Jordan Binnington mixed it up with Dallas counterpart Ben Bishop and was assessed penalties for roughing and slashing, while Stars captain Jamie Benn was sent off for unsportsmanlike conduct to start the third.
"I'm not sure exactly what all happened, how it all escalated," Blues coach Craig Berube said. "It's the playoffs. Both teams are heated. It's emotional. Things happen."
The Blues did manage to put together a solid final period, outshooting the Stars 12-5 and scoring the only goal. That one, by Robert Thomas, came at 13:44 and pulled St. Louis to within two.