Alzolay will serve as the Cubs' 29th man for Saturday's doubleheader against the Reds, Maddie Lee of NBC Sports Chicago reports.
Alzolay will be available out of the bullpen for Saturday's twin bill but should return to alternate camp following the pair of seven-inning contests. The right-hander started one game for the Cubs this season, tossing five scoreless innings, allowing two hits and one walk while striking out six.