Osich allowed a game-tying homer to the Cubs' Willson Contreras in Monday's loss. He has now blown leads in two of his last three outings and allowed at least one run to score in four of his last five appearances.
Osich struck out one batter in a perfect ninth inning and earned a save over the Brewers on Sunday.
Osich (2-0) earned the win Saturday against the Brewers after tossing one-third of an inning in relief, striking out the only batter he faced.
Osich allowed a grand slam by the Padres' Trent Grisham in Wednesday's 7-5 loss. It was the first run Osich has allowed in 5.2 innings since joining the Reds.
Osich's contract was selected by the Reds on Saturday.
Osich was reassigned to minor-league camp Saturday.
Osich was throwing his fastball between 93-95 mph in his first spring training outing, after averaging only 92 mph last season, Bobby Nightengale of The Cincinnati Enquirer reports.
Osich signed a minor-league contract with the Reds on Monday.
The Cubs outrighted Osich to their alternate training site Friday.
Osich was optioned to the Cubs' alternate training site Sunday.