Turnbull is expected to start Wednesday's Grapefruit League game against the Phillies, Jason Beck of MLB.com reports.
The Tigers announced Tuesday that Michael Fulmer has been recommended for Tommy John surgery. Daniel Norris comes to mind as a logical replacement in the starting rotation, but Norris hasn't been particularly good this spring, posting a 5.06 ERA and 9:6 K:BB in 10.2 innings. Turnbull, meanwhile, has a 2.70 ERA and 8:1 K:BB in 10 frames. If he keeps it up, Turnbull could win out and push Norris to the bullpen to begin the season.