Guillen was not in the starting lineup, but acting manager John Gibbons used him as a pinch-hitter in the eighth inning and he struck out.
"He should be ready to go," Gibbons said. "He ran around pretty good yesterday and did a lot of things, so we thought we'd give him today to regroup and then throw him in there tomorrow."
Guillen is likely to be the designated hitter in Wednesday afternoon's game against the A's.
Guillen has been out since July 23 with a ligament tear in his right knee. He had a .245 average, nine home runs and 40 RBIs in 79 games before his trip to the DL.
On the first day that Major League rosters could be expanded beyond 25, Guillen became the fourth position player on the bench. The Royals indicated earlier that September callups from the Minor Leagues would come later, perhaps after Triple-A Omaha's season ends on Monday.