Otanez (1-0) recorded the win over the Reds on Tuesday, firing two-thirds scoreless innings and recording a strikeout.
Otanez, who was removed from the Athletics' loss to the Phillies on Saturday night after taking a line drive off his pitching arm in the eighth inning, is dealing with a forearm bruise in the aftermath, the Associated Press reports.
The Athletics recalled Otanez from Triple-A Las Vegas on Saturday.
The Athletics optioned Otanez to Triple-A Las Vegas on Friday.
The Athletics recalled Otanez from Triple-A Las Vegas on Tuesday.
The Athletics optioned Otanez to Triple-A Las Vegas on Wednesday.
The Athletics selected the contract of Otanez from Triple-A Las Vegas on Sunday.
Otanez signed a minor-league contract with the Athletics on Dec. 9.
Otanez signed a minor-league contract with the Diamondbacks on Tuesday.