Duffy has already lost both of his starts against the Tigers this season, allowing a total of three earned runs in 11 innings. The 25-year-old owns a 2.86 ERA and holds the Detroit roster to a .179 average.
Detroit will send out starter Anibal Sanchez, hoping the 30-year-old can bounce back from his worst start of the season. Sanchez surrendered seven runs to the Rays on Saturday, raising his ERA to 3.18 in his third loss of the year.
Sanchez beat the Royals in his only start against them this season on June 19. He allowed just one run in seven innings, but failed to record a strikeout for the first time in his career. He enters the game Friday searching for his sixth win.
The Tigers lead the Royals by 5.5 games in the American League Central Division with three games remaining in the first half.