Nick Swisher provided an RBI single following Morgan's sac fly, while Asdrubal Cabrera and David Murphy scored the runs for the Indians, who fell to the Rays in the one-game wild card playoff last season.
Justin Masterson was solid in his third straight Opening Day start as he gave up just three hits and a walk with four strikeouts over seven innings for Cleveland, which had made the playoffs for the first time since 2007. Cody Allen (1-0) retired the final two batters of the eighth to pick up the win.
Sonny Gray had a strong start for Oakland as well, going six innings and giving up five hits and three walks with seven strikeouts. Jim Johnson (0-1) was tagged for both runs in the ninth to take the loss.
Josh Donaldson had two of the five hits for the Athletics, who won the AL West for a second straight season, but again lost to the Tigers in the divisional round.