PHOENIX -- Giants catcher Buster Posey will be monitored overnight for concussion symptoms after leaving in the third inning of Friday's game at Arizona, but manager Bruce Bochy did not seem to believe Posey's injury was too serious.
Posey became light-headed after singling to right field with one out in the third inning of the Giants' 6-3 loss. He signaled to the dugout and was removed after trainer Dave Groeschner met him at first base.
Posey took a moment after being struck in the mask on a foul tip by Paul Goldschmidt in the first inning, but remained in the game. Posey will not play Saturday, Bochy said, but could be available for the final game of the series Sunday.
"He's feeling better," Bochy said. "He had the [concussion] test done. We will monitor Buster overnight and tomorrow. If all goes well, he could be in there Sunday. Right now, it's important we keep an eye on him.
"It's a matter of what kind of night he has, how he feels tomorrow. We'll check him out again tomorrow."
Posey has been through this before. He was placed on the concussion list and missed seven days last season after being struck in the helmet by a 94 mph fastball from D-backs right-hander Taijuan Walker on April 10, 2017.
"You are not going to take any chances, especially in his situation, being there before," Bochy said. "We're hoping for the best news.
"Trust me, we are going to err on the side of caution with him because he's been through it. What's important is his health long-term, baseball. We're not going to take a risk with him."
Posey is slashing .297/.370/.411 with 22 doubles, five homers and 37 RBIs in 91 games.
Nick Hundley ran for Posey in the third inning and remained in the game Friday night. He's the only other catcher on the roster now that Pablo Sandoval is out for the season, but Bochy said that as things stand now, the Giants will not add a catcher Saturday.
"I could wake up tomorrow after talking to Buster and change the plan, but I think we are OK," Bochy said.
Infielder Chase d'Arnaud appears to be the top choice as the stopgap backup. d'Arnaud's brother, Travis, is a catcher.
The Giants understand concussion issues too well to take chances. Brandon Belt, Joe Panik and Hector Sanchez missed time the past few seasons with concussions. Belt saw a concussion specialist.