Allen will start in the second game of Saturday's doubleheader against the Pirates, Tim Stebbins of MLB.com reports.
Allen will be recalled from Triple-A Columbus to serve as the Guardians' 27th man Saturday, with the left-hander starting in Game 2 while Gavin Williams starts in Game 1. It'll be the second major-league outing of the season for Allen, with his first taking place May 25 against the Nationals, when he allowed two unearned runs on five hits and one walk while striking out seven across four innings. He's started in 16 games in Triple-A, where he has a 4-3 record and a 4.39 ERA, 1.40 WHIP and a 95:31 K:BB across 80 innings.