DENVER - Joffrey Lupul has played at the Pepsi Center enough times to know that the air can be very thin at times.

But he has also been here enough to know that the altitude can affect the way the first few shifts go more than anything else.

"It's funny, I've had times here where I thought it was really affecting me and I've had times that I haven't noticed it," Lupul said. "I put it as more of a mental thing than anything else.

"Obviously, it makes a bit of a difference, but not to the point that you can't come in and play a good hockey game. But if you start thinking about how tired you are out there, it can make for a longer night. But really, I've played here enough times where I think it doesn't really make a difference."

Well, it didn't make a difference, and then it did.

After hanging with Colorado, which should be used to the thin air of the Mile High City, the Flyers flagged late in the second period and lost last night, 2-1.

Daniel Briere tied the game in the second with a power-play goal set up by Kimmo Timonen, but the Avalanche scored with 2.9 seconds left in the period and the Flyers could not manage to catch up in the third.

The loss drops the Flyers to second place in the Atlantic Division behind the New Jersey Devils, who won their ninth game in a row earlier in the night.

"The legs were a little heavy," said Mike Richards, who was on the ice for the critical second goal. "But no different really than a night when you don't feel great. You've just got to battle through it."

Jeff Carter and Richards, both centers, were on the ice for the defensive draw that led to the go-ahead goal, but Carter took the drop because it was on his side of the ice.

"It was on [Carter's] strong side. We both decided for him to take it," he said. "[Paul] Stastny is pretty good on the draw. You can't blame [Carter]. It was just one of those things, 50-50."

The first period was more of a standoff than anything else. The Flyers were outshot, but there is nothing new in that. They were flat on the power play, passing on two chances.

Briere, who was questionable to play after taking a puck in the foot during practice Thursday, said he felt that the first period was more of a defensive battle.

"I think we turned a few pucks over on the power play," he said. "It was a period where not much was happening yet. I think both teams - not having the chance to see each other - were just kind of studying themselves in the first period."

The Flyers kept breathing through the beginning of the second and managed a huge kill on a five-on-three.

It didn't work the way it did in Minnesota.

Denver bounced right back and took a 1-0 lead at 7:26.

Jaroslav Hlinka walked in deep but was kept to the outside. He still found a tiny hole over Martin Biron's shoulder with a quick wrist shot.

The Flyers tied things back up again on Briere's power-play goal. Timonen walked the puck across the top of zone and faked a shot, sending a blistering pass down to the side of the net for Briere to onetime it home.

"We kept the puck to the outside and made them chase the puck. I think they got tired after a minute and 45 seconds," Briere said. "Kimmo did a great job selling the play, selling the whole thing. He found me back door. I give total credit to him."

The Flyers had a great chance to push the lead with a five-on-three power play for 36 seconds but couldn't take advantage.

"Part of the game that got away was that five-on-three," coach John Stevens said. "We had it for 36 seconds, we turned it over right away, we got back in the zone and turned it over again and now you're wasting time and giving them momentum.

"I thought we could have gotten something done there. If you don't score, at least you create a couple of chances to give you momentum so it kind of slipped away there."

Things were looking good until the final seconds of the period, when the Flyers broke down and Timonen got flagged for hooking in front at 19:40.

Carter lost the defensive zone faceoff and the Avalanche pressed the situation, pinning the Flyers in and then retaking the lead. Ryan Smyth made a nice feed from behind the net to Milan Hejduk in front and Hejduk took care of business with just 2.9 left in the second.

It's not a good thing for the Flyers, who came into the game 1-8-1 when they start the third period from behind.

Colorado held every Flyers push, and then the post got in the way. Late in the period, Mike Knuble came around the net and clanked one.

"I think their guy laid down and I kind of hit him and it altered a little bit. It hit their guy right next to the post," he said.

"We did a lot of good things in our opinion. We were fighting the puck a little bit. We had a hard time grabbing pucks tonight, and we weren't able to get anything laying there. They did a good job of swatting pucks in their crease and we couldn't quite get to them." *