In St. Louis, Doug Wilson scored a first-period goal and set up Denis Savard in the same period.
Chicago leads the series, two games to one. The Black Hawks, who scored a 104 points in the regular season, can end the series tonight in St. Louis.
Right wing Rich Preston set up Wilson's first playoff goal by digging the puck out of the corner after Tom Lysiak shot wide of the net. Wilson beat Mike Liut to the short side of the goaltender from 16 feet.
Four minutes later, the all-star Chicago defenseman set up the winning goal by Savard after Black Hawks goalie Murray Bannerman got a loose puck.
Wilson's 70-foot pass from the Chicago red line was on target to the fleet Savard behind the Blues' defense near center ice, and the Black Hawks center sent a rising slap shot into the far corner a stride behind the blueline.
Chicago swarmed over St. Louis at the outset, permitting the Blues only five shots on Bannerman during the opening period. Rookie Mark Reeds finally broke through, beating Bannerman with bad-angle shot off Bannerman's pads with 17:11 left.
Chicago lost left wing Al Secord with a double game-misconduct penalty, which will carry over to tonight's game.