The White Sox slugger, who is second in the majors with 38 home runs and the league leader in walks (96) and strikeouts (194), played in all three games of the team's series against the Minnesota Twins on Monday, Tuesday and Wednesday after previously sitting Sept. 1 and 2 because of the injury.
Dunn is carrying a batting average of .208 with a .485 slugging percentage and .340 on-base percentage this season for Chicago.
"He has that side (injury) again," White Sox manager Robin Ventura said prior to Friday's game, according to the report. "Just trying to take care of it and make sure nothing gets worse. It's just one of those keeps coming back every once in a while."
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