Turnbull will begin the season as the Tigers' No. 3 starter, Anthony Fenech of the Detroit Free Press reports.
Turnbull is slated to start Saturday against the Blue Jays in Toronto and will follow Jordan Zimmermann and Matt Boyd in the rotation. The 26-year-old beat out Daniel Norris for the spot, which opened up when the team announced that Michael Fulmer will get Tommy John surgery and miss the season. Without a ton of standout pitchers around him, Turnbull could lock himself into the rotation for 2019 and possibly beyond if he pitches well out of the gate.