Having seemingly shaken the flu bug, Guillen was going to be back in Hillman's lineup.
But as the team bus pulled away for its trek to Mesa, Ariz., Guillen wasn't aboard. He remained in Surprise, Ariz., for another day.
"At the end of yesterday, he was ready to go he thought," Hillman said. "But he came in this morning and said, 'Trey, I'm aching. I need another day of flushing this out.'"
Hillman didn't hesitate to tell Guillen, one of the key players going into the season, to stay in Surprise and not worry about the game with the Cubs.
Guillen, though, told Hillman that he'd try to work out in the Surprise complex and would then get a few at-bats in a Minor League game there on Wednesday, a day off for the Royals.
Hillman told him not to. He said he wanted Guillen to rest another day or so.
"I told him we've gotta go come Thursday, so get it flushed out," Hillman said.
The Royals manager also said that veteran infielder Mark Grudzielanek (back problems) and catcher Miguel Olivo (sore groin) should be ready for a return to duty on Friday, Hillman said.
Olivo caught two bullpen sessions on Tuesday and hit in the cage without problems.
"If he comes back tomorrow and his body feels good, we'll ease him into a Minor League game situation where we can control it a little bit," Hillman said.
Justice B. Hill is a senior writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.