CHICAGO -- White Sox catcher A.J. Pierzynski was out of the starting lineup Tuesday and is listed as day to day with a mild right oblique strain.

Pierzynski suffered the injury while swinging during Chicago's 7-4 win against the Twins on Monday.

The injury doesn't affect Pierzynski defensively, but it bothers him at the plate. White Sox manager Robin Ventura said the club will monitor Pierzynski on Wednesday, as well, with the hope he can avoid aggravating the injury.

"He mentioned it toward the end of last night's game," Ventura said. "So he's going to take today off, maybe tomorrow. Depends on how he feels when he comes in tomorrow. But definitely today, he'll be out."

Pierzynski, 35, leads all American League catchers in RBIs (50) and slugging percentage (.507), while ranking second in batting average (.287), home runs (16) and runs scored (40).

Backup Tyler Flowers started Tuesday in place of Pierzynski.