Walls was diagnosed with hyperextended middle and ring fingers on his left hand following Wednesday's game against the Blue Jays, Ryan Bass of Rays.tv reports.
Walls suffered the injury while sliding into second base in the fifth inning. He was able to play through the injury and finish the game, but manager Kevin Cash said after the game that Walls will likely sit out Thursday's series finale as a precaution. Ben Williamson will presumably fill in as Tampa Bay's shortstop and could continue to do so if Walls is forced to miss any additional starts.