Assuming the simulated game goes well, Duffy will pitch next Monday at Cleveland.
The extra rest does not mean Duffy suffered a setback. Both he and manager Ned Yost were adamant about the left-hander's good health before Monday's series opener against Chicago.
"The only thing we do know, is he feels good," Yost said.
Duffy exited his Sept. 6 start vs. the Yankees after throwing just one pitch with shoulder inflammation, an injury that caused him to miss his next start.
"It was very necessary to come out of the game in New York and it was very necessary to skip a start, but I think I'm ready to go," Duffy said.
Duffy tossed a promising, 20-pitch bullpen on Sunday, giving him hope that he could return in the second of a three-game series vs. the White Sox.
"The bullpen, I felt very sharp. I let my last five pitches really go 100 percent and I had life on it, if not more life than I've had in the last two months," Duffy said.
But ultimately, Kansas City erred on the side of caution with Duffy, currently in the midst of his best Major League season.
"What that just does it just makes sure Danny is both mentally and physically ready for his next start," Yost said.
Jackson Alexander is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.