MONTREAL - The drop-off, from Hart Trophy-winning defenseman to fringe NHLer, is a large one.

Starting tonight, when the Flyers take on the Canadiens at the Bell Centre, they will have no choice but to play without that top-caliber player in Chris Pronger and replace him with two players - Andreas Lilja and Matt Walker - who have been swapped in and out of the lineup this season like interchangeable parts.

"We'd much rather have Chris in there, because he is a world-class player," coach Peter Laviolette said. "But he's not available. You know, injuries are a part of [a long season]. Every team goes through it. You have to deal with it.

"In saying that, we were able to manage without him and we're going to have to do it moving forward. We've got guys, we've got this covered. We'll miss him, but we'll get by."

The Flyers will certainly miss Pronger, as the stats bear witness. Last season, when Pronger sat out 32 regular-season games with knee, foot and wrist injuries, the Flyers' win percentage was 61 points lower.

According to Hockey Prospectus, their goals-for/goals-against total shrunk from plus-37 with him to plus-3 without him. Their goals-against skyrocketed from 2.46 per game (eighth in the league) to 2.91 per game (23rd in the league).

That all might not sound like a lot, but when extrapolated to an entire 82-game season, Pronger in the lineup equates to 10 more points.

Simply put, Pronger is worth five wins.

Even without Pronger, the Flyers are in better shape than most teams with Kimmo Timonen, Braydon Coburn, Matt Carle and Andrej Meszaros anchoring the back end.

"We've got great defensemen back there, a good core," Laviolette said. "I think we've got a good team in place defensively. We'll have to pick up the pieces when he's not there."

Those pieces are Lilja and Walker.

Walker, who played briefly with Pronger in St. Louis, said he left a message with his thoughts and concerns for Pronger's health in a voicemail yesterday.

"It's tough to see anyone go down, especially with your eye," Walker said. "Hopefully, Chris is back - the sooner the better - because it'd be best for the team to get him back on the ice."

Walker is the recipient of a nice gift from Pronger, in the form of a regular spot in the lineup. Monday was just Walker's second game of the season, after sitting out six games as a healthy scratch.

Coincidentally, it was Pronger's serious knee injury in 2002-03 that freed up a roster spot for Walker to break into the league with the Blues.

"It's a great opportunity to get some more games and more ice time," Walker said. "It's an opportunity that you've got to take advantage of as a player."

Walker has averaged 13:46 in ice time over his two games. In the six games Walker missed, Lilja averaged just a shade less at 12:39. Combined, those two ice times don't meet Pronger's career average of 27:29 since the ice-time stats were first kept in 1998-99.

Pronger has never finished lower than eighth in the league in average time since the stat became official.

Laviolette famously does not release lineups ahead of time, but there are two ways to approach playing a Pronger-less lineup to minimize risk. Lilja and Walker could be paired together and played sparingly. Or, they could be paired with one of the other veteran defenseman to keep everyone fresh and then pare down their minutes late in games.

Laviolette said he swapped Lilja and Walker through the first eight games to keep both players fresh. It appeared that Walker was used in matchups against more physical teams, like Toronto and Ottawa.

"I wanted to keep people playing," Laviolette said. "I don't want one guy out of the lineup for too long. They're two different players; they're both steady, more of defensive defensemen.

"I think Matt brings a little more of an edge to his game, you look at the game in Ottawa [last week] and he fought twice. He brings a presence about himself."

Strapped by the salary cap, the Flyers do not have enough room for an extra defenseman like Erik Gustafsson or Oskars Bartulis, unless Pronger's health deteriorates and he is added to the long-term injury list. That means it is up to Lilja and Walker, two veterans with more than 800 games between them, to step up and shoulder the load.

"It's not the way you want to go in, but there is an opportunity for me," Lilja said. "We're all going to have to chip in and take over his minutes. It's a tough job."

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