D-backs prospect Tyler Mark walked off under his own power after being struck in the head by a line drive off the bat of Vladimir Guerrero Jr. in the third inning of an Arizona Fall League game on Wednesday night at Salt River Fields.

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The pitcher delivered an 80-mph slider that Guerrero lined back up the middle with an exit velocity of 103.24 mph, per Statcastâ„¢.

The ball ricocheted off Mark into the third-base dugout for a ground-rule double. Dude’s lucky he didn’t lose an eye.