Barring any setbacks, Cespedes would then potentially be available to pinch-hit for the start of a three-game series with the Rockies on Tuesday in Denver. A starting assignment is less likely.
"He's probably available to pinch-hit today," Melvin said, "but whether or not we feel comfortable about him doing that, I'm not sure yet. He's a little better and we'll again evaluate him after batting practice."
Cespedes sustained a strained left hamstring in Thursday's win against the Rangers in Oakland, and the absence of his bat has been magnified through the first two games in Phoenix, where the A's have dropped a pair of contests to the D-backs.
Oakland is 19-16 with Cespedes in the lineup and 7-18 when he doesn't play. At the time of his injury, the rookie had hits in six straight plate appearances.
PHOENIX -- A's manager Bob Melvin wasn't ruling out a Yoenis Cespedes appearance on Sunday before his club's series finale against the D-backs, but he also acknowledged it would be ideal to rest the outfielder through Monday's off-day.