Nationals pitcher Edwin Jackson walks to the mound as New York’s Kirk Nieuwenhuis, right, celebrates with third base coach Tim Teufel as he heads home with a two-run home run in the fourth inning. (RAY STUBBLEBINE/REUTERS)

The firepower in their bullpen makes it easy for the Washington Nationals to envision life without Drew Storen, until the ninth inning arrives and the score is tied. Storen will see orthopedist James Andrews on Tuesday for a second opinion on his elbow, a visit that could end with him sidelined for half the season and the Nationals needing to fill a lot of ninth innings.

Monday night at Citi Field, they chose Henry Rodriguez. In a calamitous ninth inning, the unbeaten New York Mets rallied for a walk-off, 4-3 victory that left the Nationals’ record at .500, their second baseman momentarily dazed, Edwin Jackson without a winning Nationals debut and their successor to Storen still in question.

Rodriguez walked the first batter of the ninth, melted down trying to field a bunt and then allowed Daniel Murphy’s game-winning single, all without recording an out. Rodriguez had thrown like the most dominant pitcher on the planet all spring, including against the batter he struck out to end the eighth inning Monday. But then he found out what the Nationals and Storen know: The ninth inning is different.

“This is the first time in a pressure situation, but he’s certainly capable of doing that,” Manager Davey Johnson said. “I’m very pleased with Henry and where he’s at. Just one of those things.”

If the ninth inning shook Rodriguez, he did not show it Monday night. After Murphy’s single, Rodriguez walked off the mound slowly, staring straight ahead, betraying no emotion. In the clubhouse, reporters gathered around him. Rodriguez had never before given a group interview in English. Monday, he agreed to stand up and speak.

The Mets’Daniel Murphy reacts as his walk-off single drops in to score runner Mike Baxter. (RAY STUBBLEBINE/REUTERS)

“Nobody wants to go out there in the ninth and walk the first batter,” Rodriguez said. “I feel pretty bad about myself.”

Rodriguez overwhelmed hitters all spring training, harnessing his 100-mph fastball and physics-defying curveball. In his season debut on Saturday, he struck out the final three batters he faced in a three-run game. The question remained: How would Rodriguez handle the tightest of situations?

“I’m thinking the same,” he said. “I feel the same.”

Rodriguez led off the ninth inning by walking pinch hitter Mike Baxter on five pitches. Mets Manager Terry Collins called on Ruben Tejada to bunt, and on a 2-2 pitch he pushed one back to Rodriguez. That is when the damage began.

Rodriguez scooped the ball, turned and looked to second. He may have had a play, but the umpire blocked his view of Ian Desmond covering the base. Rodriguez turned to first base. His double-clutch forced him to rush. He side-armed a throw, which caused the ball to veer toward the runner and dart toward the dirt.

Tejada reached first base at roughly the same time as Rodriguez’s low throw to second baseman Danny Espinosa, covering first. As Tejada collided with Espinosa, he smacked him incidentally on the head with his elbow. The ball squirted away. Espinosa was dazed.

“I just needed a second,” Espinosa said. “I’m fine.”

An errant throw from Nationals pitcher Henry Rodriguez bounces behind second baseman Danny Espinosa after Ruben Tejada's ninth-inning bunt. (Kathy Willens/Associated Press)

Espinosa scampered after the ball in foul ground, having lost his glove in the collision. When Baxter slipped between third and home, Espinosa held the ball for a moment, not wanting to throw behind Baxter and let him score. He fired to third — “a perfect strike,” third baseman Ryan Zimmerman said — just late as Baxter scrambled back to the bag.

With runners on second and third and no outs, the result became almost a formality. Then again, Rodriguez has the kind of stuff that makes three straight strikeouts more than a dream. Not Monday. Murphy flared a 1-0, 96-mph fastball into shallow right field, a walk-off single.

“I’m sure Henry is the maddest person in here,” Zimmerman said. “He’s going to be a person that helps this team out a lot and wins a lot of games for us. It happens. Things like that happen. Henry is going to win us a lot more games with his stuff and his pitching than he is going to lose us games like that.”

Rodriguez’s games will more often be decided by his throws to the plate than to bases. And the Nationals have other late-inning options, too, with 35-year-old veteran Brad Lidge and his 224 career saves along with Tyler Clippard, who Johnson views as too valuable to use outside of his versatile setup role.

“They did a great job of going out and getting Lidge and guys like that,” Zimmerman said. “We have a more-than-capable bullpen. Hopefully, it will hold up while [Storen]’s gone.”

The end overshadowed the Nationals’ 10 hits, which helped stake them to a 3-0 lead after three innings. Making his first start since the Nationals signed him a one-year, $11 million deal in February, Jackson could not hold the lead. He pitched five innings and allowed three runs on two hits and a walk, limited to 78 pitches because Johnson lifted him for a pinch-hitter.

One of those pitches stayed with Jackson most. With two outs in the fourth, Jackson walked Josh Thole, and then Kirk Nieuwenhuis launched a two-home run to right field, a thunderbolt that tied the score at 3, even though the Nationals had outhit the Mets.

After the inning, as he walked off the mound, Jackson covered his face with his glove and screamed at himself, concealing his mouth until he reached the dugout. Jackson smacked his glove with his right hand as he hopped down the stairs. Jackson castigated himself not for the walk, which came on what he called “close pitches,” but for the 87-mph slider he left over the plate’s heart to Nieuwenhuis.

“Man on first, two outs and a 2-2 count, the slider’s supposed to be buried,” Jackson said. “It just stayed up, and he did what he was supposed to do with it. He hit it for a home run. Other than that, I felt good.”

By the end of the night, he joined a quiet clubhouse, awaiting word on their closer, left to wonder what the ninth inning would look like without him.