The Brewers reinstated Koenig (elbow) from the 15-day injured list Sunday, Todd Rosiak of the Milwaukee Journal Sentinel reports.
An MRI on Koenig's left elbow showed swelling but no structural damage, Adam McCalvy of MLB.com reports.
The Brewers placed Koenig on the 15-day injured list Saturday with left forearm tendinitis.
Koening will serve as the Brewers' opening pitcher in Saturday's game against the Reds, Curt Hogg of the Milwaukee Journal Sentinel reports.
Koenig will serve as the Brewers' opening pitcher for Monday's game in Philadelphia, Mark Feinsand of MLB.com reports.
Koenig will open Saturday's game against the Red Sox, Adam McCalvy of MLB.com reports.
Koenig is opening Friday's game against the Red Sox.
The Brewers recalled Koenig from Triple-A Nashville on Saturday.
The Brewers optioned Koenig to Triple-A Nashville on Saturday.
The Brewers recalled Koenig from Triple-A Nashville on Sunday.