The Ottawa Senators locked up a key part of their roster on Friday, re-signing forward Chris Kelly to a four-year $8.5 million contract, breaking down as just over $2.1 million per season against their cap.

Kelly was eligible for unrestricted free agency in July and it had been speculated the Senators might lose him to the UFA market because of cap constraints. He’s a versatile checking forward who can play center or wing and also chip in offensively.

His signing could make it tougher however for the Senators to find sufficient cap space to re-sign key free agents such as Andrej Meszaros, Antoine Vermette, Cory Stillman and Mike Commodore.

The list of potential targets for offer sheets next summer grew smaller on Friday when the Ottawa Senators announced the signing of center Jason Spezza to a contract extension.

Spezza, who was eligible for restricted free agent status in July, received a seven-year contract worth $49 million, or $7 million per season against the Senators salary cap.

TSN.ca breaks down the deal as follows:

For the first three seasons (2008-09 to 2010-11) Spezza receives $4 million in base salary with a $4 million signing bonus.

For the next two seasons (2011-12 to 2012-13) he’ll receive $6 million in base salary with a $2 million signing bonus.

He’ll receive $5 million in 2013-14 and $4 million in 2014-15.

The site also reports that, like linemate Dany Heatley, Spezza’s new contract also comes with provisions for a no-trade clause.

Some might question if Spezza is worthy of this contract, as the deal is close in dollars per season to Heatley’s new $7.5 million per season contract, but Spezza’s numbers over the past two seasons are comparable to Heatley’s. Indeed, they might’ve been similar had Spezza not missed an average of 15 games per season in that period to injury.

The bottom line is the Senators weren’t going to break up one of the best offensive “one-two punches” in the NHL. Spezza and Heatley power the Sens offensive attack and with both now in their prime should continue to do so over the next five or six years.

With this signing the Senators have now committed over $41 million in salaries for next season for 12 players. Assuming the salary cap increases to $52 million for 2008-09 that’ll leave just over $10 million to fill out the rest of their roster.

Three key players to re-sign will be defenseman Wade Redden and checking forward Chris Kelly, both eligible for unrestricted free agency in 2008, and defenseman Andrej Meszaros, like Spezza eligible for RFA status.

Kelly might accept a raise from his current $1.262 million to between $2-$2.5 million per, while Meszaros could be in line for around $3 million per, a figure a rival team might be willing to pay via offer sheet should the Senators balk.

The big question is Redden, who’s earning $6.5 million this season. Senators GM Bryan Murray claims he wants to retain Redden but unless he’s willing to accept a pay cut that doesn’t seem possible. Even if Murray were to trade Martin Gerber and his $3.7 million per season salary between now and next July that still might not free up enough to retain Redden, re-sign Kelly and Meszaros and still flesh out the roster for 2009-10.