"We took him out tonight as a precaution. He seemed to be OK after getting hit in the side of the head with the bat, then just looking at him after he stepped out twice in that at-bat," Mattingly said, referring to Grandal's fourth-inning flyout, which came after he got his bell rung. "When he came back in, we were paying close attention. Hopefully it's nothing, but we'll see."
If Grandal is deemed to be concussed, he'll be eligible for the seven-day disabled list MLB instituted in 2011.
"I'm not sure of the [concussion] protocol. It's been a huge issue the past couple years and I know everyone had to take a test in Spring Training," Mattingly said. "He passed all those and I was sitting there when he was asking all the questions."
Triple-A catcher Austin Barnes was pulled from Oklahoma City's game in Las Vegas in the sixth inning Friday night, indicating he is the likely candidate to join the Dodgers if Grandal misses time.
Grandal was first hit on the side of the head by the follow-through of Yangervis Solarte's bat when he popped out to end the third inning.
Then in the top of the fourth, Grandal took a Matt Kemp foul tip off the face mask. At the end of each of those innings, Grandal was checked in the dugout by VP of medical services Stan Conte.
Grandal then flied out to deep center to end the bottom of the fourth, but walked back slowly to the dugout and Conte motioned to Mattingly that Grandal could not continue.
A.J. Ellis took over behind the plate.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.