The St. Louis Blues were already an underdog entering their series with the Detroit Red Wings. And now, not only are they down 3-1, but they have lost Chris Pronger, their captain and arguably their most valuable all-around player, to a torn knee ligament.

What once was a mere mountain range for the Blues to climb has now become Mount Everest.

At age 38, Al MacInnis is neither as strong nor as young as Pronger, so the Blues can't ask him to take on any more ice time. Pronger was averaging more than 30 minutes a game. Because Pronger went down in the first period, MacInnis had to play nearly 33 minutes in Game 4.

Another defenseman will have to fill Pronger's void. Marc Bergevin, a healthy scratch the past two games, is a likely candidate. Rich Pilon has played only eight games all season and zero in the playoffs. I spoke to him Thursday, and he has clearance to play. But is it fair to suddenly throw him on the ice in Game 5 against the Red Wings?

Without Pronger, the only approach the Blues can take is to play a suffociating, defensive game and try to grind out a low-scoring game. They will be in trouble if they play their up-tempo, attacking style.

The Blues need at least two forwards back in deep to help defensemen Jeff Finley, Bryce Salvador and Bergevin or Pilon, if either or both play. To survive against the Red Wings, the Blues need to play to whatever strength they have left, and that is their defensive game.

Bill Clement, who won two Stanley Cups with the Philadelphia Flyers, is a hockey analyst for ESPN.