McClanahan (forearm) will be placed on the 15-day injured list Thursday, Marc Topkin of the Tampa Bay Times reports.
McClanahan was lifted from his start Wednesday against the Yankees after experiencing left forearm tightness in the bottom of the fourth inning. There is no exact diagnosis yet, but the 26-year-old ace is headed for imaging scans and is expected to seek out multiple opinions in an effort to get to the root of the issue. He'll be sidelined through at least mid-August, and perhaps far longer. More should be known in the coming days.