The Kansas City Royals purchased López's contract in August 1974, shortly after he led the Mexico City Reds to the Mexican League World Series title in four straight games. The Royals also purchased the contracts of Mexican League players Orlando Cepeda and 16-year-old Germán Barranca in the same month. The Royals planned to use López in the September pennant race and throughout the next season. Lopez pitched in eight games in 1974, and he was bought back by the Mexico City Reds in early 1975.