Fischer, 81, will act as the Royals' bullpen coach on Friday and Saturday during the games against the Oakland A's. He'll step in for Steve Foster, who will move from the bullpen to the dugout as acting pitching coach.
Those moves were prompted by pitching coach Dave Eiland's departure to his Florida home for his daughter Nicole's high school graduation.
Fischer is the Royals' senior pitching advisor, joining the organization in 2007. He pitched in nine seasons, 1956-64, for five clubs including the Kansas City A's.
So he'll fit right in on Saturday afternoon when the first 20,000 fans receive a replica 1960 Kansas City A's cap, in commemoration of that year's All-Star Game in K.C., and former A's will be honored before the game.