Darvish, who underwent surgery on March 17, 2015, began his rehab assignment on May 1, meaning it expires on May 30. But this is expected to be his final start as long as everything goes well.
He would replace Cesar Ramos in the rotation.
T.R. Sullivan has covered the Rangers since 1989, and for MLB.com since 2006. Follow him on Twitter @Sullivan_Ranger and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.