PHILADELPHIA -- The Giants lost one of their cornerstone players on Friday night, when catcher Patrick Bailey was forced to depart a 4-3 series-opening defeat to the Phillies after taking a foul ball off his face mask.

Bailey started behind the plate, but was shaken up after taking a direct hit during Alec Bohm’s at-bat in the first inning. He returned to catch starter Jordan Hicks in the second, but he signaled for head athletic trainer Dave Groeschner and manager Bob Melvin after Nick Castellanos reached on a one-out throwing error by third baseman Matt Chapman.

After a brief discussion, Bailey exited the game and was replaced by backup catcher Tom Murphy. The Giants announced that Bailey departed with blurry vision, though he wasn’t placed in concussion protocol and was being evaluated by team doctors after the game.

“I think he’s doing a little better,” Melvin said. “I think he had some blurry vision. Obviously, we were going to be proactive with that. The doc saw him, and we’re monitoring him right now.”

Bailey, 24, previously landed on the concussion list last September, when he missed six games following a home-plate collision with then-Cubs infielder Jeimer Candelario. He’s been wearing a Q-collar -- an FDA-approved, externally worn device that gently compresses the neck to keep more blood volume inside the head and reduce the brain’s movement upon impact -- to try to prevent more concussions, but it wasn’t enough to stave off his latest injury scare on Friday.

“It’s terrifying, right?” Murphy said. “I feel for that kid deeply. Hopefully he figures out maybe a better mask system, something better for him. I know he’s wearing the neck thing to help him with that. I just really hope he’s OK.”

If Bailey needs to miss time, the Giants could call up Blake Sabol, who is the only other catcher on the 40-man roster now that former top prospect Joey Bart is no longer with the organization. Sabol, 26, spent the entire 2023 campaign with San Francisco after sticking as a Rule 5 Draft pick, but he opened this year at Triple-A Sacramento, where he entered Friday batting .243 with a .702 OPS and one home run over 21 games.

Losing Bailey for an extended period of time would be a huge blow to the Giants, who have leaned on the second-year backstop for not only his Gold Glove-caliber defense, but also his steady production at the plate. He’s one of the few bats that has been consistently performing for San Francisco early this year, hitting .278 with an .800 OPS and three homers through 25 games.

“Hopefully it’s not a loss,” Melvin said. “He is central to kind of everything we do.”

“I just kind of joke around with him and call him Yadi [Molina] Jr.,” added Hicks, who gave up four runs (two earned) over four innings. “He’s just a great young talent in my eyes.”

Bailey drew a leadoff walk in his lone plate appearance in the second and came around to score on Thairo Estrada’s two-run double, but the Giants couldn’t deliver the knockout blow when they had Phillies right-hander Aaron Nola on the ropes. An uncharacteristically wild Nola issued four walks in a 46-pitch inning and fell into a two-out, bases-loaded jam, but managed to limit the damage by getting Jorge Soler to pop out to end the inning.

The Phillies erased the deficit by scoring three runs in the third, which began with a second error by Chapman, who couldn’t hang on to Kyle Schwarber’s pop-up in shallow left field. The Phillies took advantage of another defensive miscue to extend their lead to 4-2 in the fourth, when the speedy Trea Turner singled, stole a base and then scored all the way from second on a passed ball by Murphy.

Murphy tried to recover the ball and throw to the plate, but his toss sailed a bit wide, allowing Turner to slide in just ahead of Hicks’ tag.

“I saw [Turner] rounding third, and I was like, ‘Let’s go,’” Hicks said. “Just a tough throw. I tried to turn my body and make the play. I thought I got him. I guess good heads-up play by him.”

Soler had another chance to break the game open when he came up with the bases loaded and no outs in the seventh, but he pushed across only one run after grounding into a double play. The Cuban slugger is only 3-for-26 with runners in scoring position this season, a major reason why the Giants have now been held to three runs or fewer in eight consecutive games.

“We all feel like he’s going to get a hit in those situations,” Melvin said. “It just hasn’t happened yet.”