Defenseman Kevin Shattenkirk has agreed to a four-year, $17 million contract extension with the Blues, a league source has told the Post-Dispatch.

On the day that the Blues officially announced an extension with forward Patrik Berglund, the Blues have locked up one of their top young defensemen.

In 2012-13, Shattenkirk, 24, netted five goals, 23 points and was a plus-2 in 48 games, tying him for the 24th most points in the NHL among defensemen. He was second on the Blues behind Alex Pietrangelo (24).

In 201 career games, Shattenkirk has 23 goals and 109 points and is a plus-18.

So now the Blues have two of their restricted free agents signed. Still remaining are Pietrangelo, Chris Stewart, Kris Russell and Jake Allen.

Recently, Blues general manager Doug Armstrong said that there was no priority list deciding which players would be signed first.

"They're all individual negotiations," Armstrong said. "I don't really see one affecting the other in my mind, the way they slot into our team."

The NHL's free-agency period opens July 5th. It's been pushed back from the usual date of July 1 under the league's new collective bargaining agreement to give clubs two days (July 3-4) to talk to free agents. This avoids the potential of teams tampering with players before their existing deals expire.

Once the free-agency period begins, the Blues' RFAs will be permitted to receive offer sheets from other clubs. But Armstrong, who has indicated that the team would match any outside offer, doesn't seem fazed that the process could go past July 5.

"Whether (the RFAs are signed) in June, July, August, some of these might go all the way to November ... you never know," Armstrong said. "Both sides have to sign on the dotted line when they're happy.