Paul Konerko was held out of the Chicago White Sox lineup due to a sore back Thursday night against the Kansas City Royals.
Konerko leads the club with a .305 batting average and has 23 home runs with 69 RBIs. He has hit .257 since his average peaked at .399 on May 27.
"I don't know if it's real bad, but it's enough that he needs a day," White Sox manager Robin Ventura said, adding Konerko's back has been bothering him "off and on."
Ventura said he is optimistic Konerko would be able to play Friday against the Los Angeles Angels.
Alex Rios, who is hitting .301 with 24 home runs and 87 RBIs, replaced Konerko in the cleanup spot. Kevin Youkilis, who normally bats second but is in an 0-for-11 skid and hitting .133 over his past 17 games, was dropped to the sixth for the first time.