The Cardinals have traded for Red Sox pitcher John Lackey, according to Jon Heyman of CBSSports.
In exchange for Lackey, the Red Sox will receive pitcher Joe Kelly and outfielder Allen Craig.
The Red Sox also sent minor-league pitcher Corey Littrell to the Cardinals.
Lackey, 35, has posted a 3.60 ERA with 116 strikeouts and 32 walks over 137 1/3 innings this season.
The Cardinals opened Thursday at 56-50, one game back in the Wild Card race and in third place in the National League Central.
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- Chris Johnson