J.D. Martinez hit the go-ahead solo home run in the fourth inning, and Detroit held on to post a 2-1 victory over the Royals, snapping their 10-game win streak in Thursday's finale of a four-game series.
Miguel Cabrera drove in the other run for the Tigers, who avoided a sweep and moved a half-game back of their foes for first place in the AL Central.
Billy Butler doubled twice and knocked in the lone run for the Royals, who hadn't tasted defeat since June 6 at home against the Yankees.
Danny Duffy (4-6) also worked seven innings, but took the loss despite letting up just two runs on three hits with five strikeouts.