CHICAGO -- After suffering a slight concussion in Tuesday's game, Ryan Doumit was out of the lineup and unavailable for Wednesday's game. The Pittsburgh catcher is listed as day-to-day, though he likely won't be back in the starting lineup until Friday at the earliest.

Doumit took three foul balls off his mask on Tuesday, the last of which came on a ball hit by White Sox outfielder Jermaine Dye, with one out in the sixth. Doumit was slow to get up out of his crouch after the ball ricocheted off his mask, and then stepped back in a daze for a few seconds.

He stayed in to finish the inning, but was then replaced by backup Raul Chavez in the bottom of the seventh.

"We're being overly cautious with a concussion," manager John Russell said. "He's feeling better today."

Doumit did undergo a concussion test, which Russell said "came back very good." As a result, there is no expectation that Doumit will have to be out more than a few days.

Doumit was held out of most pregame work on Wednesday and did minimal on-field running. The plan is for that pregame work to increase some on Thursday, as the Pirates are targeting a potential return behind the plate for him when the team opens up a nine-game homestand Friday.

This doesn't mark the first time that Doumit has missed action due to a concussion. He missed four starts just over a year ago, also after suffering a slight concussion. The fact that this is the second time in 13 months that Doumit has had a concussion explains why the organization is remaining extra guarded on pushing Doumit back on the field too quick.

For Doumit, the minor setback has come not long after he was finally able to make his return to the field after recovering from a strained left thumb. He has played in 10 games since the injury, going 11-for-35 with four homers and seven RBIs. The switch-hitting catcher also garnered National League Player of the Week honors last week.

Continuing on the injury front, right fielder Xavier Nady continues to show signs of improvement with his strained left shoulder. He continues to throw, though there is no set date for when Nady is expected to begin swinging a bat or catching again.

Fellow outfielder Jason Bay was back in the lineup on Wednesday after missing one game due to illness.