Sources: Interest in Astros' Pence exploding

HOUSTON Interest in Pence has exploded since Carlos Beltran exited the market Wednesday, multiple baseball executives who spoke with the Astros told ESPN.com.

The Phillies, Braves, Reds and Red Sox were among a group of six to eight teams discussing deals for Pence, sources confirmed. An official of one team described the Astros as having "an open mind" on trading Pence, even though they've continued to tell clubs that called that they don't want to trade him and would need to be overwhelmed to make a deal.

ESPN.com reported Wednesday that the Astros had turned down a trade proposal earlier this week in which the Phillies offered their best pitching prospect, Jarred Cosart, and their best hitting prospect, Jonathan Singleton, along with another pitching prospect.

The Astros have been telling clubs they need four "sure-thing" players in return in order to deal Pence, who is signed for this year at $6.9 million and can't become a free agent until after the 2013 season.

Jayson Stark is a senior baseball writer for ESPN.com.