The Pittsburgh Pirates have emerged as a dark-horse candidate to acquire Jon Lester from the Boston Red Sox, according to sources.

Pittsburgh has one of the best farm systems in baseball, giving them the tools to put together a nice package for the left-hander.

Josh Bell is at the center of talks, according to sources.

The Red Sox continue to ask for a lot in return for Lester even though he will be a free agent at the end of the season.

Bell, 21, hit .335/.384/.502 at Class A Bradenton before a recent promotion to Double-A.