Manager Davey Johnson looks on as catcher Wilson Ramos is helped off the field. (Joe Robbins/GETTY IMAGES)

As they surged further into first place Saturday night, the Washington Nationals might have pushed closer to their breaking point. They have withstood injuries to, among others, their cleanup hitter, their closer and their $126 million right fielder. As Wilson Ramos lay prone behind home plate at Great American Ball Park, they also had to contemplate surviving also without their bedrock catcher.

The Nationals’ 2-1 victory over the Cincinnati Reds may have come with a cost. Ramos twisted his right knee while chasing a passed ball in the seventh inning, immediately dropped to the ground and remained there for several minutes. He had to be helped off the field by two trainers, his face contorted into a grimace.

Ramos went for an MRI exam after the game as the Nationals made plans to summon a catcher from their farm system. Saturday night, they had not learned how long they would be without Ramos. But they knew, with Michael Morse, Jayson Werth and Drew Storen already on the disabled list, they would face another test.

“Losing Willy is a big, big blow,” Manager Davey Johnson said. “I don’t know how bad it is. I have a bad feeling he tore something in there and it’s going to be a while. Just keep our fingers crossed. But right now, it’s not good at all.”

Ramos earlier had provided one of the game’s pivotal blows, a 409-foot home run to center field in the fifth inning, his third this season. Second baseman Danny Espinosa continued to extricate himself from a vicious, year-long slump, crushing his second homer in as many games to put the Nationals ahead in the sixth. Jordan Zimmermann made his scant support stand up, allowing one run and five hits in seven innings while striking out nine. “The best I’ve felt all year,” Zimmermann said.

Rather than bask in their third straight victory, though, the Nationals absorbed what may have been a potentially crushing development. Ramos, 24, is considered a primary piece of the team’s foundation, “our backstop for the next 10 years,” General Manager Mike Rizzo has said.

Ramos endured a harrowing kidnapping saga in his native Venezuela this winter, spending 48 hours abducted by captors. He arrived at spring training grateful and eager to move past the incident. Though he has regressed on defense, Ramos had been one of the Nationals’ most consistent hitters this season.

In the seventh inning, Zimmermann fired a 93-mph fastball beyond the right edge of the plate. Ramos lunged for the ball, which deflected off his glove and trickled behind him. As he scooped up the ball, his spike caught in the grass and his knee buckled, bending unnaturally sideways.

“He was trying to plant on his back foot,” Zimmermann said. “It twisted a little bit.”

Ramos crumpled to the ground and lay on his stomach, his face in the grass, until Nationals trainers arrived. Ramos came off the field with both arms around a Nationals trainer, no weight on his right leg.

Jesus Flores replaced Ramos, shepherding Tyler Clippard and Henry Rodriguez — who struck out the side on 10 mind-bending pitches in the ninth — through two scoreless innings. Eight Nationals players, including many of their best, have spent time on the disabled list this year.

“It goes back to what Davey said in spring training,” shortstop Ian Desmond said. “He wants to build a team that has bench players that are perfectly capable of carrying the load if necessary. I think he did that. I think Flores is an outstanding catcher. And I think we’re going to be fine. Of all the injuries — obviously, Wilson is a huge part of this team. But Flores is a very established catcher.”

Flores, 27, became the Nationals’ everyday catcher in 2009, but a torn labrum in his right shoulder sidelined him for nearly two full years before he returned last season. Also a native of Venezuela, he is close friends with Ramos.

“It is sad,” Flores said. “I’ve been there. I know he doesn’t feel very good. I hope it’s nothing serious and he’ll be fine. I went and talked to him, and he said he doesn’t feel well.”

For a backup, the Nationals will likely call up veteran Carlos Maldonado, who impressed in spring training, from Class AAA Syracuse. The other options would be Jhonatan Solano, who recently returned from an injury for Syracuse, and Sandy Leon, a young, defensively proficient catcher at Class AA Harrisburg.

Ramos’s injury overshadowed everything, but the game otherwise belonged to Zimmermann. All five hits he allowed were singles. The Reds scored their only run in the first, only after Drew Stubbs reached on fielder’s choice on a routine groundball. Zimmermann’s nine strikeouts gave Washington starters 31 over their last three outings, a span of 18 innings.

“I had command of everything,” Zimmermann said.

The Nationals (21-12) gave Zimmermann enough support even after leaving the bases loaded in the fourth and fifth. Espinosa provided the difference with his emphatic home run to lead off the sixth inning, his second homer in two days after going 104 at-bats without one. He crushed the first pitch reliever Jose Arredondo threw 397 feet, into the right-field stands. Espinosa stared at the ball for a moment in the batter’s box. There was no doubt.

“I’m just trying to be aggressive if I get a pitch in the zone,” Epsinosa said. “I’m not just going up there and just swinging. I felt myself doing that a little bit in Pittsburgh.”

The Nationals would overcome their wasted opportunities. Whether or not they overcome their latest injury, one of the saddest moments of their season, is unknown.

“We’re brothers in here,” Desmond said. “We’ve got great chemistry. We just lost another brother.”

Said Johnson: “We’ve got pretty good depth here. We’ve got a lot of talent here. But I think we’ve had enough [injuries].”