Allen will start the first game of Friday's doubleheader versus the Tigers, Tim Stebbins of MLB.com reports.
All four of Allen's appearances since he was recalled in mid-August have come out of the bullpen. However, he has made 20 starts between the majors and minors in 2026 and will be pitching on five days' rest, so he should be capable of providing five-plus innings if he's pitching well.