CHICAGO - Chris Pronger had his uniform on straight, his helmet was positioned properly, and his skates were laced tightly.

It's his game that was upside down, and the Flyers caught a strong dose of what happens when their premier defenseman, the player who was having the most significant impact in the Stanley Cup Finals, has a rough night.

They lose.

It doesn't take a hockey aficionado to realize the Flyers would be lounging at their summer cottages if No. 20 wasn't patrolling the blue line, using his mean edge, his stick, and his vast experience to fend off trouble.

Certainly, Pronger is entitled to a bad game. He had one in Game 3 of the Eastern Conference Finals against Montreal, and the Canadiens got their only win of the series, 5-1.

But Pronger's timing couldn't have been much worse as his struggles helped lead the Flyers down the path of a 7-4 loss to the Blackhawks on Sunday.

Chicago's win left the Flyers with no margin for error, trailing by three games to two with Game 6 Wednesday at the Wachovia Center.

Pronger, booed when he carried the puck, was on the ice for six Blackhawks goals, and he was in the penalty box when Chicago built the lead to 5-2 on a power-play goal by Dustin Byfuglien late in the second period.

But Pronger the leader wasn't wringing his hands over his poor performance. He didn't need to be reminded that he was on the ice for six Chicago goals. But when he was, he smiled and said, "Thanks. Thanks for the green jacket. That's very nice of you. I appreciate that."

When pressed about what happened, he added, "Well, I think you just stated it. I guess there's really not much else to say."

The Pronger-Byfuglien matchup has been one of the more fascinating subplots to the series. Byfuglien is the 257-pound power forward who came into the series with eight playoff goals. Pronger made sure he was stuck at eight, refusing to yield the front of the net to the bullish Byfuglien, relentlessly unnerving him.

So Byfuglien must have felt as if he was sprung from a trap as Pronger sat in the penalty box on his first goal. Byfuglien later added an empty-net goal. In between, he put some heavy hits on Pronger.

Pronger characterized Byfuglien's performance with some light sarcasm.

"I guess he's well-rested, so . . ." he said.

Does that mean he hadn't done much? "I guess he's well-rested," Pronger repeated.

On the Blackhawks' first goal, Pronger attempted to block Brent Seabrook's shot. But the shot went off his shin pad and got past goalie Michael Leighton for Chicago's second power-play goal of the series.

"They got a lot of good bounces to go their way," Pronger said. "The first one deflected in off my shin pad. I can't remember the second one. You guys know. It's all on video."

Pronger's influence on this series had been so forceful that it led Blackhawks coach Joel Quenneville to break up his top line of Jonathan Toews, Patrick Kane, and Byfuglien, a trio that had combined for 22 goals and 34 assists before the Finals. That line had one goal and four assists in the first four games.

"I don't know if the changes really mattered that much," Pronger said. "Anybody can make a play when you've got all day to make them."

Pronger has averaged more than 30 minutes of ice time a game during the Finals. The Blackhawks have tried to wear him down by pounding on him. He took more punishment in Game 5 than any other. The most notable hit was by Byfuglien, who drilled him into the boards in a corner behind the Flyers' net and sent him sprawling to the ice in the second period.

The good news for the Flyers is that Pronger gets two days of rest before Game 6, and that he has yet to play poorly two games in a row.