Right-hander Gavin Floyd will start the opener against Toronto left-hander Brian Tallet.
Floyd was scheduled to start Saturday's game, a duty that now will go to White Sox left-hander Mark Buehrle. The Blue Jays' starter for that game has yet to be announced, after scheduled starter Ricky Romero, a rookie left-hander, went on the disabled list Thursday with a strained right rib cage muscle.
The moves essentially give Buehrle, who is 2-0 with a 3.00 ERA, an extra day of rest and push up Floyd, who is 2-1 with a 4.74 ERA.
"We have to do it to keep everything on track," said White Sox manager Ozzie Guillen. "I don't want to move people around, but anytime we have the chance to move them, we will. The more rest they get, the better for us. ... I want all those guys [rested] in July, August, September. The stronger we keep them, the better ballclub we have."
Sunday's scheduled matchup between Chicago right-hander Jose Contreras (0-3, 8.04 ERA) and Toronto ace right-hander Roy Halladay (3-1, 3.72 ERA) remains unchanged.
Pete Kerzel is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.