Ronald Fairman, chief of vascular surgery at the Hospital of the University of Pennsylvania, made the diagnosis.

"I got hit with a shot [from Andrei Markov] in Game 4 against Montreal," the 33-year-old defenseman said. "It's been getting sorer and sorer every day. We thought we'd get it checked out because it did not get better and they found a blood clot. . . . This has been an awful day for me.

"It's the most disappointing thing in my hockey life, for sure. . . . It's an awful feeling. I was expecting to play. How many times in your lifetime do you get to play in a conference final?"

An MRI exam on Wednesday failed to reveal a problem, general manager Paul Holmgren said, but Fairman found a small blood clot yesterday. Timonen was placed on blood thinners.

"I asked the doctor what could happen and what was the worst-case scenario," Timonen said. "He said, 'If you get hit there again, the blood clot might break up and go down to your toes and we'd have to cut off your toes.' That's not a very good scenario."

Timonen said he suffered a similar injury to the same ankle five years ago while playing for Nashville and developed a clot as well.

The Flyers initially treated the injury as a bone bruise, icing the ankle. They called for an MRI test when the defenseman's pain persisted.

"It continued to bother him more and more each day," Holmgren said. "To rule out a fracture, we checked it out. It's a quite serious thing. He needs to go on blood thinners. He's not going to be available."

Holmgren said there was a small chance that in a week's time there would be improvement, but he was not holding out much hope that Timonen would play in this series.

Timonen initially told The Inquirer he was out for the remainder of the playoffs. However, during a conference call with reporters, the Finnish defenseman said Fairman told him the only hope to return was if things went well over the next 10 days and the clot disappeared.

"Kimmo did get some glimmer of hope. Who knows?" Holmgren said. "They don't know. The clot could respond to the medicine he is taking. It's right where he ties up his skates, and it would be difficult [to play]. I'm not going to hold out any hope he's back in this series. We'll see after that."

Timonen is the club's best two-way defenseman. He was expected to play against Pittsburgh's Evgeni Malkin. His loss greatly affects the Flyers' chances to win the conference finals.

He was the shutdown defenseman against Washington's Alexander Ovechkin in the first round and Montreal's Saku Koivu in the second. His 34 blocked shots in the postseason were second on the team to Jason Smith (37).

The composure Timonen brings to the ice, both carrying the puck and defending against the top offensive players in the league, cannot be replaced. Outside of goalie Marty Biron, he is the Flyers' best defensive weapon.

"It is what it is. We have to deal with it," Holmgren said. "It gives someone else an opportunity to step up. Everybody else has to do their part. Obviously, you can't replace a player who does what Kimmo does for us."

Veteran Jaroslav Modry will likely fill Timonen's spot, coach John Stevens said. Modry has far more experience than rookie Ryan Parent.

"I played in Game 5 in Montreal, but it was really hurting me," Timonen said. "I have to be honest, I didn't expect this result."

Timonen did not make the trip to Pittsburgh.