Allard will replace Corey Kluber (shoulder) in the rotation, Evan Grant of the Dallas Morning News reports.
The Rangers were dealt a blow Sunday when Kluber was diagnosed with a torn teres major muscle in the back of his right shoulder. He's been shut down for four weeks, which means he might not pitch again for six weeks. Allard, a former first-round draft pick, took a regular turn in the Rangers' rotation over the final two months of 2019 with mixed results. The left-hander was stretched out as a starter during summer camp, but it's unclear how many innings he'll be ready for the first time out. The Rangers have a few days off early in the season and will not need a fifth starter until Aug. 8.