SAN DIEGO – Keibert Ruiz never had time to react, nor could he have anticipated what happened in the top of the fourth Monday night at Petco Park.

The Nationals’ 10-6 victory over the Padres was marred somewhat by the freak incident that forced Ruiz to an area hospital for a CT scan after he was struck by Josh Bell’s errant foul ball on the left side of his head.

Ruiz was watching the game from the top railing of the dugout when Bell fouled off Stephen Kolek’s pitch and sent the ball on a direct line toward the third base dugout. Nationals players and coaches barely saw it whiz past their heads, and nobody saw it carom off the dugout’s back wall and strike Ruiz on the side of his head.

The 26-year-old wasn’t wearing his catcher’s gear, because his spot in the lineup was approaching. He immediately grabbed his head and headed down the dugout steps and toward the visitors’ clubhouse as director of athletic training Paul Lessard followed close behind.

“When he went down, we kind of got scared a little bit,” manager Davey Martinez said. “He had a nice lump on his head.”

Ruiz never lost consciousness, and he was coherent as the medical staff asked him questions. But he was sent to the hospital for the CT scan, which would help determine if he suffered a concussion or any other type of head injury.

“A little concerned right now,” Martinez admitted. “Hopefully he comes out of it OK.”

Riley Adams quickly replaced Ruiz in the lineup and behind the plate, finishing out Monday’s game. The longtime backup catcher, a San Diego-area native who turns 29 on Thursday, wound up going 0-for-4 with three strikeouts. He’s batting just .097 (6-for-62) with one walk and 28 strikeouts this season, though three of the six hits have been home runs (including on Friday night at Dodger Stadium).

With no other catchers on the active roster, the Nationals had to contemplate what they would do in the nightmare scenario Adams also got hurt during the game. Infielder Amed Rosario and outfielder Alex Call each wound up catching warmup pitches between innings when Adams was strapping on his gear in the dugout.

Given that concern, the Nats probably will need to summon Drew Millas from Triple-A Rochester to at least fly to San Diego today and be available in case Ruiz needs to be placed on the injured list.

The catcher position has been among the Nationals’ biggest problem areas this season. Ruiz and Adams have combined for a .556 OPS, the second-to-lowest mark for any team’s catchers in 2025. Giants catchers (.522 OPS) are the only ones with worse numbers.

Ruiz, who signed an eight-year, $50 million extension prior to the 2023 season, is batting .247 with two homers (hit in the season’s first two games) and 24 RBIs in 66 games to date. Adams, who is out of minor league options, can’t be sent to the minors without first passing through waivers.

Millas, meanwhile, has a .680 OPS at Triple-A, down considerably from his .879 mark a year ago. In 31 big league games across parts of the last two seasons, he’s batting .259 with a .330 on-base percentage and .694 OPS

The Nationals can only wait to learn more about Ruiz’s condition and whether it will require an IL stint or not before determining any next steps.

“I love that kid,” Martinez said. “He wants to play every day. He’s a gamer. So hopefully it’s just precautionary, and he comes back and he’s good to go.”