"He feels nothing. No reason not to expect him pitching sometime in Detroit," Royals manager Ned Yost said.
Right-hander Felipe Paulino is doing well on a rehabilitation assignment with Double-A Northwest Arkansas and could be close to returning. Yost wanted to see how Everett Teaford did as Duffy's stand-in on Friday night against the Twins before making any pitching adjustments or changes.
Teaford lasted just four innings, giving up four runs on eight hits. Yost said after the Royals' 7-6 victory that he had no roster moves to announce.
There could be a change in the order of the rotation.
One possibility is to push back right-hander Luke Hochevar, who normally would pitch on Monday night at Detroit but is favoring a sore ankle. Duffy could slide into Hochevar's spot or start later in the series.