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01/24/2013 2:31 PM ET

White Sox claim Zach Stewart off waivers from Pittsburgh

The Chicago White Sox have acquired right-handed pitcher Zach Stewart off waivers from the Pittsburgh Pirates.

Stewart, 26, combined to go 1-4 with an 8.58 ERA (34 ER/35.2 IP) in 20 games (three starts) last season between the White Sox and Boston.  The 6-foot-2, 205-pounder was 1-2 with a 6.00 ERA (20 ER/30.0 IP) in 18 games (one start) with Chicago before being traded to Boston with infielder Brent Lillibridge on June 24 in exchange for third baseman Kevin Youkilis.

Stewart also made 11 starts for Class AAA Pawtucket in 2012, going 3-5 with a 3.94 ERA (26 ER/59.1 IP) and 42 strikeouts.  He was traded to Pittsburgh on November 28, 2012 in exchange for pitcher Kyle Kaminska and designated for assignment by the Pirates on January 17.

He originally was acquired by the White Sox from Toronto on July 27, 2011 with pitcher Jason Frasor in exchange for pitcher Edwin Jackson and infielder Mark Teahen.

With Stewart's addition, the White Sox 40-man roster increases to 39.

This story was not subject to the approval of Major League Baseball or its clubs.