The major league-leading Angels also reinstated infielder Grant Green from the 15-day disabled list on Sunday before their series finale against the Athletics.
Rasmus had six strikeouts during three innings of one-hit ball in his first career start Saturday night. He was optioned back to Triple-A Salt Lake to rest for a few days, manager Mike Scioscia says.
Los Angeles used eight pitchers in its three-hit shutout of the A's, but elected to replace Rasmus with Green instead of a fresh arm. The Angels have a day off Monday.
Green missed 37 games with a lumbar strain. He is batting .313 for the Angels.