Diaz was removed from Friday's game against the Padres with left knee patellar tendinitis, Marc Topkin of the Tampa Bay Times reports.
Diaz went 2-for-2 with a two-run homer and a walk in Friday's game, but he had to be lifted for a pinch runner after he singled to left field in the fourth inning. It's unclear if he'll need to spend time on the injured list, but Jonathan Aranda, who entered as the pinch runner, could see an uptick of playing time at first base if Diaz needs to miss any amount of time.