If there is a more improbable second-round matchup than this, we'd like to hear about it.
Two teams that looked like they'd be easy pickings in the first round thanks to injury and a dearth of scoring or goaltending instead found some reservoirs of will and toughness. Now the winner will be heading to the Eastern Conference finals. Go figure.
Boston never showed any quit, twice coming back from two-goal deficits to beat third-seeded Buffalo in six games. The Philadelphia Flyers have been cooling their heels after upsetting the second-seeded New Jersey Devils in five games. The Flyers, though, will be without three players they began the series with: Jeff Carter, Simon Gagne and Ian Laperriere. They'll also have to hope veteran backup Brian Boucher can continue his magical run after being thrust into the starting role.
1. Attrition malnutrition: The Flyers lost two key offensive components in Game 4 against the Devils, as Gagne and Carter suffered foot injuries while blocking shots and will not be available in this series. That means there is additional pressure on youngsters Claude Giroux (six points in the first round), James van Riemsdyk and Ville Leino, who played in just one game in the first round, to pick up the slack offensively. Laperriere will also be lost to the team; he suffered a brain contusion and mild concussion after blocking a shot.
2. The fine line between physical and psycho: The good news for the Flyers is they allowed just four goals on a whopping 32 power-play opportunities against the Devils. But they will be courting disaster if they continue to go to the box at the rate they did in the first round. The problem for them is that one of the areas in which they'll need to assert themselves is physicality. The Bruins manhandled Buffalo through the early parts of their series, and the Flyers will be determined to stand tall, as all Flyers teams do when the going gets tough. Word of warning, though: The Bruins scored six power-play goals on 22 chances and, with Savard back in the fold, will be even more dangerous.
3. Killer B's: A big factor in Boston's first-round upset of Buffalo -- and a focal point heading into the second round -- was the success of its penalty-killing unit against Buffalo. The Sabres were the only team not to score a power-play goal in the first round (the Bruins shut them out on 19 straight attempts). The Flyers were potent with the man advantage against New Jersey, scoring eight times on 29 attempts. Stay tuned.
4. We can be heroes: One of the enduring themes of any playoff season is the unsung or unlikely players who step forward to make significant contributions. You can certainly put Miroslav Satan in that category. People thought so little of Satan's ability he wasn't even playing when the Bruins signed him midway through the season. Over the years, some have questioned his heart, but he was huge for the Bruins in the first round with two goals (both game winners) and three assists. He'll have to man up against a much more physical Flyers team to keep his hero status intact.
On the other side of the playoff fence, there is Daniel Carcillo, more known for being a master of mayhem. He had two goals and an assist versus the Devils, one an overtime game winner. He will be in his element against a very physical Bruins team.
5. The Savvy factor: Savard played only 41 games this season and hasn't played in almost two months thanks to Cooke's blow to the head. Will Savard be gun-shy? How long will it take to get his timing -- so much a part of his finesse game -- back? If he can get into a groove, the Bruins' chances of success immeasurably increase.
• Zdeno Chara versus Chris Pronger: They won't necessarily match up against each other, but this series, likely to be very physical, may turn on which of the team's big men exerts themselves more prominently. Pronger was brought in by Philadelphia for this time of year and he hasn't disappointed, logging 29:03 a night in ice time, scoring twice and adding three assists. Chara, banged up with a broken nose, is averaging 28:46 and also had two goals, including a game winner. They live to make life miserable for opposing forwards, and the team that's most miserable at the end of the series will likely be going home.
• Boston: Rookie netminder Tuukka Rask didn't get on the final Calder Trophy ballot, but he's been terrific in his first playoff experience. He held the Sabres to 14 goals in six games and has a .927 save percentage. Marco Sturm, one of the Bruins' veteran offensive players, has zero points. That won't cut it against the Flyers.
• Philadelphia: Those who criticized Brian Boucher down the stretch (yours truly included) are eating a healthy dose of crow. The goalie was rock-solid, allowing just eight goals on 134 shots in the first round for a 1.59 goals-against average. His save percentage of .940 is out of this world. Scott Hartnell continues his up-and-mostly-down season with just one assist through five games. Good news is that the often-undisciplined winger only had four minutes in penalties in the first round.
• This series should be a bit of a throwback, with every square inch of ice hotly contested. We didn't believe in the Bruins down the stretch and we didn't believe in them against Buffalo, and we find no reason to start now. The Flyers' top-end guys like Mike Richards, Kimmo Timonen, Daniel Briere and Pronger assure us a third straight Philadelphia-Pittsburgh playoff clash. Flyers in seven games.
Scott Burnside covers the NHL for ESPN.com.