"I got a bona fide bullpen session in," Shields said. "We simulated a few innings today, so it was quite a bit of work today. I'm ready to go.
"I just wanted to work out a few kinks in the bullpen, so I thought that was a good setting."
Minor League right-hander Gregory Infante started in place of Shields, allowing two runs on one hit with three walks and four strikeouts over two innings in a 5-2 loss to the Brewers.
Continuing to work toward an Opening Day roster, the White Sox outrighted outfielder Rymer Liriano and left-hander Giovanni Soto to Triple-A Charlotte.
The moves clear two spots on the 40-man roster for the White Sox to potentially add non-roster invitees.
Manager Rick Renteria said Friday the team will likely finalize its Opening Day roster Saturday.
The White Sox also have yet to announce their fifth starter, with Dylan Covey and Anthony Swarzak as potential candidates.
"We still have options of Covey and Swarzak, and we still have options in the Minor Leagues available to us," Renteria said. "We've been keeping our eye on Covey and Swarzak quite a bit."
No set DH
Instead of having one player serve as the team's primary designated hitter, Renteria plans on using the slot to rotate regular position players through.
"Most guys don't want to put themselves into a position where they are a DH," Renteria said. "I certainly don't see any of our guys as a true DH. I see them being able to play the positions they are now.
"I think it is more using it to get guys off their feet. Day [game after a] night [game], things like that. It is a long season."
Andrew Gruman is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.