(Sports Network) - A pair of cross-state rivals will begin the Eastern Conference finals tonight, as the second-seeded Pittsburgh Penguins host the sixth-seeded Philadelphia Flyers in Game 1 of the best-of-seven series at Mellon Arena.

What is being dubbed as the "Battle of Pennsylvania" should be a highly- competitive and physical series, that is, if the regular season meetings between these clubs are any indication of how this matchup will go.

The Flyers won the season series against Pittsburgh, 5-3, but Philadelphia posted four of those victories prior to the All-Star break, before the Penguins really started to click.

The Penguins then won three straight in the series before Philadelphia posted a 2-0 victory on the final day of the regular season.

Pittsburgh swept the Ottawa Senators in four games during the opening round and then notched a five-game series victory over the rival New York Rangers. The Penguins are 8-1 in the playoffs and have won 19 of their last 25 games dating back to the regular season.

The Flyers outlasted Washington in seven games during the opening round and disposed of top-seeded Montreal in five tests to reach the conference finals for the first time since 2004.

Philadelphia will now try to get to the Stanley Cup finals for the first time since getting swept by Detroit in 1997.

The Flyers are 3-0 all-time in playoff series against the Penguins with the most recent meeting coming in the 2000 conference semifinals. Philadelphia fell behind 0-2 in that series, but won the final four outings, including a memorable five-overtime matchup in Game 3.

However, the Flyers received some devastating news Thursday, when it learned that top defenseman Kimmo Timonen will likely miss the entire Pittsburgh series with a blood clot in his left ankle. Timonen, an All-Star in each of the past two seasons, is averaging nearly 25 minutes of ice time in the playoffs and was used by the Flyers to help contain Alex Ovechkin in the Washington series and Montreal's Alex Kovalev in the next round. The 33-year- old Finn was expected to take the same role against Pittsburgh's Sidney Crosby and Evgeni Malkin.

Timonen is also an integral part of Philadelphia's power play and has six assists in 12 playoff games this year.

Crosby and the Penguins were bounced out by Ottawa in the first round of the 2007 playoffs, but are now in the conference finals for the first time since 2001, when they lost to New Jersey.

Crosby, who battled a high ankle sprain for a lengthy stretch in the second half of the regular season, played in just four of the eight meetings against the Flyers this year, but has more points in his career against Philadelphia than other team. In 20 career tests against the Flyers, Crosby has registered 16 goals and 37 points.

Crosby and Malkin lead Pittsburgh this postseason with 14 points apiece.

Flyers forward R.J. Umberger is coming off a huge series against the Canadiens. After scoring just one goal in the Washington series, Umberger exploded for eight markers in the second round. He was just two goals shy of the franchise record for most tallies in a series. Tim Kerr scored 10 times in seven games during the 1989 division finals against Pittsburgh.

Umberger is also a native of Pittsburgh and has played the best hockey of his career against his hometown club. He has 18 points (8g, 10a) in 23 career games versus the Pens, including six goals and five assists in eight tests this year.

Despite Umberger's huge series against the Habs, Danny Briere is still leading the Flyers with 14 points (8 goals, 6 assists) this postseason.

Philadelphia has received excellent goaltending from Marty Biron so far this postseason. Biron's playoff numbers (2.72 GAA, .914 save pct.) aren't eye- popping, but the 30-year-old backstop has made big save after big save in his first-ever playoffs. The 395 shots Biron has faced is also the most against any goaltender in these playoffs.

Penguins netminder Marc-Andre Fleury has also been terrific between the pipes in the playoffs, going 8-1 with a stingy 1.76 goals against average and .938 save percentage. The 23-year-old goaltender is 18-3-1 dating back to his last 13 starts of the regular season.

The Pens were an excellent home team during the regular season, going 26-10-5 at the Igloo. They are 5-0 in the Steel City during the postseason. Philadelphia was 21-15-5 as the visiting team this year and 4-3 on the road in the playoffs.

Game 2 of this set is scheduled for Sunday night in Pittsburgh.