"Same spot," Jackson said. "We just want to be cautious with it and not push it."
Jackson said the soreness didn't become an issue until Thursday. He was set to spend Friday getting treatment on it with the hope of returning to the lineup Saturday.
Jason Beck is a reporter for MLB.com. Read Beck's Blog and follow him on Twitter @beckjason. Bobby Nightengale is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.