Rivera was optioned to Triple-A Colorado Springs on Thursday.
With Scooter Gennett coming off the disabled list Thursday, Rivera was the likeliest candidate to be sent down to clear a spot on the active roster. He slashed an unplayable .196/.213/.261 at the plate through 46 at-bats with the Brewers prior to his demotion. The 24-year-old infielder will head down to Triple-A to see more regular playing time.