Osuna, who has 19 saves, did not appear in the ninth inning on Friday, when the Blue Jays surrendered four runs in a 5-4 walk-off loss to the Royals. Toronto manager John Gibbons said after the game that Osuna was unavailable because he wasn't feeling well.
Osuna made it clear on Saturday that his problem is not physical.
"I feel great physically," Osuna said. "It's just more mentally. It has been a couple of days that I have felt this way. I really don't know how to explain it. I just feel anxious. I feel like I am lost a little bit right now.
"This has nothing to do with me being on the field. I feel great out there. It's just when I am not on the field that I feel weird and a little bit lost. I wish I knew how to get out of here and how to get out of this. We are working on it."
Osuna was in uniform prior to Saturday's game, and he said he hoped to be available to pitch.
"I am going to try," Osuna said. "But nothing is for sure. We will see."
Robert Falkoff is a contributor to MLB.com based in Kansas City who covered the Blue Jays on Saturday.