Hamilton sat out for the 13th time in 14 games Thursday night when the AL West champion Angels took on Seattle.
Hamilton missed 11 games with an injured shoulder before returning Tuesday, but the 2010 AL MVP felt a new pain in his upper body during batting practice this week. Manager Mike Scioscia hopes the new injury is minor.
Hamilton is batting .263 with 10 homers and 44 RBIs in an underwhelming season. The Angels haven't missed his bat while streaking to the division title and the major leagues' best record in September.
The Angels rested their top position players on Thursday in the series finale against the Mariners.