Just a few weeks ago, a first-ever playoff matchup between Philadelphia and Ottawa didn't seem possible. But, both the Flyers and Senators stumbled down the stretch -- the Flyers went 2-7-1-0, the Senators went 4-4-1-1 -- setting up this unlikely No. 2 vs. No. 7 first-round playoff series.

This series will turn on the Senators' willingness to compete in the tough areas of the ice and their ability use their speed off the wing to take advantage of the Flyers' not-so-mobile defensemen.

Ottawa's skilled wingers -- like captain Daniel Alfredsson, Marian Hossa, Martin Havlat and Shawn McEachern -- all can create offense at high speed. Offensive-minded Flyers forwards, like John LeClair and Mark Recchi, will have to commit to slowing them down in the neutral zone. If they don't, and Senators' wingers can gain the offensive zone with speed, life will be very unpleasant for the less speedy Flyers defensemen like Luke Richardson, Chris Therien and Dan McGillis.

Conversely, Richardson, Therien and McGillis will be happy to punish those goal-happy wingers along the wall and in front of goalie Roman Cechmanek (or Brian Boucher). In past playoffs, these Senators haven't been willing to pay the physical price to score big goals. As a result, the Senators have been first-round losers in five of their six playoff appearances.

And, this year, the Senators won't be able to place the blame on the departed center Alexei Yashin, who managed only one assist in last season's sweep by Toronto.

The Senators won the season series, 2-1-1, and were 1-0-1 in Philadelphia. (The Senators are a very impressive 5-1-2 in their past eight trips to Philly.) In their two regular-season victories, Hossa ran wild, registering three goals and three assists as the Sens outscored the Flyers, 10-3. The Flyers must stop Hossa.

Ottawa must be willing to play on the edge physically. Entering the series, it should plan on taking a few penalties, if necessary, to show it won't be pushed around. In the past two playoffs, the Senators were roughed up by the Leafs. They didn't respond on either occasion and were beaten both times.

And taking some statement penalties against the Flyers doesn't pose the same risk as it does against other teams. The Flyers, despite having an All-Star lineup, own the worst power play of all playoff teams and finished the season 28th in the league at 13.2 percent (39 for 296). Meanwhile, Ottawa's penalty killing finished 17th in the league at 84.4 percent (259 of 307), but it was one of only seven teams to post double digits in shorthanded goals (11).

If the Senators big-time players play big and they match the Flyers' intensity level, they might advance to the second round for the second time in six tries. If their stars opt to stay out of the traffic areas, they'll soon be out of the playoffs.

E.J. Hradek writes hockey for ESPN The Magazine. E-mail him at ej.hradek@espnmag.com.