Jax was removed from Saturday's start against the Phillies due to a lower-back contusion, Marc Topkin of the Tampa Bay Times reports.
Jax took a 104 mph comebacker off the bat of Trea Turner in the third inning, which ended up being a groundout for the Phillies shortstop to end the inning. Steven Matz took the mound for the Rays in the fourth, but it could have been a precautionary decision to remove Jax from the game, seeing as Tampa Bay is locked in as the top seed for the American League playoffs. His status will be worth monitoring over the coming days leading up to the ALDS opener Oct. 3.