Santillan will serve as the Reds' opening pitcher in Tuesday's game versus the Cubs, Mark Sheldon of MLB.com reports.

Cincinnati selected Santillan's contract from Triple-A Louisville on Saturday.

The Reds reassigned Santillan to minor-league camp Friday, Gordon Wittenmyer of The Cincinnati Enquirer reports.

Cincinnati re-signed Santillan on Thursday to a minor-league contract with an invitation to spring training.

Santillan cleared waivers Friday and was sent outright to Triple-A Louisville, Charlie Goldsmith of The Cincinnati Enquirer reports.

Santillan was designated for assignment by the Reds on Tuesday.

Santillan has given up four earned runs on six hits and two walks while striking out seven in six innings across six relief appearances for Triple-A Louisville since the Reds optioned him to the minors July 19.

Cincinnati added Santillan as the 27th man for Tuesday night's game against the Giants.

The Reds optioned Santillan to Triple-A Louisville on Saturday.

Santillan (1-0) picked up the win in Thursday's game against Washington. He allowed one hit over a scoreless ninth inning in a 5-4 extra-inning win.