Hernandez, 31, immediately grabbed his right forearm after getting hit by the line drive off the bat of Cubs catcher Victor Caratini. Trainers came out to attend to Hernandez, and he was taken to the Mariners' facility for X-rays, which came back negative. He will be reevaluated Tuesday and is listed as day-to-day.
Hernandez missed considerable time last season with shoulder issues and struggled to a 4.12 ERA while compiling just 118 innings.
Last May, a line drive off the bat of Caratini struck Cardinals pitcher Daniel Poncedeleon in the head during a Triple-A game. Poncedeleon required emergency surgery to alleviate pressure on his brain followed by a couple of weeks in intensive care in Des Moines, Iowa, and then three months of inactivity at home in Florida.
Poncedeleon returned to the mound Sunday, pitching two innings of three-hit, one-run ball for the Cardinals against the Houston Astros.