Friday night, the Nationals’ most important series since baseball returned to Washington began with the biggest nightmare in their history. They sent their ace to the mound and took a nine-run advantage against the Atlanta Braves, their primary competition in the National League East, and then watched it evaporate. They sent the game into extra innings against the league’s most dominant closer, which only enhanced the heartbreak.

As rain fell on Nationals Park, Washington absorbed a loss that defied comprehension. The Nationals’ showdown against the Braves started with an 11-10, 11-inning knee to the stomach. They battered Atlanta for five innings, taking a 9-0 lead before Stephen Strasburg allowed four runs in the sixth, their bullpen yielded four more in the eighth and Tyler Clippard blew his second save this week in the ninth.

Danny Espinosa played hero with a monstrous, game-tying solo home run off of Craig Kimbrel in the bottom of the ninth. But the Nationals’ defense betrayed Tom Gorzelanny in the 11th. Paul Janish’s no-out, bloop single scored Dan Uggla, who had reached second on Ryan Zimmerman’s throwing error and moved to third on a passed ball by backup catcher Sandy Leon. Add it up, and the Nationals suffered their largest blown lead ever.

“This is probably the worst game I’ve ever managed in my life,” Manager Davey Johnson said, harping on his handling of the bullpen. “There’s a few things I’d take back. I don’t even want to go there. But that’s my part of the game. Obviously, when they score 10 runs, that’s my fault. There’s a lot of little things. I don’t want to go there. I’ve got to live with it.”

The Nationals could have taken a 4½ game lead in the division standings and guaranteed finishing their four-games-in-three-days series in first place. They will show up for Saturday’s doubleheader with a 2½-game lead, a worn bullpen and shot nerves. Disasters could once be cast aside as a byproduct of bad baseball. Now, they eat at your stomach like a promise broken.

“It hurts. It hurts bad,” Clippard said. “We’ve got to win that game. Bottom line. It’s a frustrating loss. Big game. Nothing you can do about it. You’ve got to move on.”

Afterward, General Manager Mike Rizzo paced through a silent clubhouse, forcing a smile. “Is this a funeral?” he asked. “Did somebody die? We’re in first.”

In the eighth, Drew Storen allowed both hitters he faced to reach base. Johnson immediately called on Sean Burnett to quell the rally, but on a messy, rain-soaked night he yielded two walks and two hits with two outs. Suddenly, after RBI hits from Chipper Jones and Freddie Freeman, a blowout had turned into a one-run nail-biter.

The disaster continued in the ninth. Clippard walked Uggla on five pitches, threw a wild pitch through Leon’s legs and then hit Janish as he tried to sacrifice bunt. Pitching coach Steve McCatty trudged to the mound with no outs and two men on base, trying to calm his closer.

Clippard started light-hitting David Ross with two balls, trying to fix the footing on the mound between pitches. He came back to strike out Ross after a generous call on a 3-1 fastball. Michael Bourn sealed Clippard’s demise when he clobbered a triple off the scoreboard in right-center. Uggla and Janish raced home as Michael Morse tracked down the ball, and shocked settled over the stadium.

“I just haven’t been real sharp lately,” Clippard said. “It’s kind of just something you go through in a season. That’s probably all I can say. It’s probably my worst stretch I’ve had in a long time. It hasn’t been real good lately.”

After the Braves staggered the Nationals, they sent in Kimbrel to finish them off. He has become the best closer in baseball. His stirkeout of Ian Desmond to start the inning was his 40th out of the past 80 batters he had faced, with just five hits allowed in that span.

Espinosa stepped into the batter’s box, undaunted by the moment and unafraid of Kimbrel. He took a ball, and Kimbrel fired a 1-0, 98-mph fastball down the plate’s heart. He challenged Espinosa. And Espinosa clobbered the ball to left-center, an opposite-field homer that smacked off the side wall of the visitor’s bullpen. The game was tied at 10.

Gorzelanny plowed through a 1-2-3 10th, but the Nationals crumbled in the 11th. Zimmerman made a dazzling stop on Uggla’s groundball in the hole, but unleashed a wild, spinning throw to first. It skipped by Adam LaRoche, and the winning run moved into scoring position with no outs.

“That’s the play,” Zimmerman said. “I would do it again if I had the same opportunity.”

Janish attempted to bunt Uggla to third, but Leon, the backup Johnson inserted in the seventh inning after Jesus Flores left with a sore back, could not corral it. After the passed ball, Janish blooped a single over Desmond, who was drawn in at shortstop. Uggla cruised home, and the Braves’ dugout exploded.

The Nationals went out in order in the 11th, and they could only wonder what went wrong. Their nine-run lead was built by three-run homers by Morse in the first and Zimmerman in the fourth off Braves starter Tommy Hanson. Morse’s blast clattered the blue seats in front of the Red Porch and traveled an estimated 465 feet, the longest homer ever hit at Nationals Park.

In ideal circumstances, Johnson may have shortened Strasburg’s workload with a 9-0 lead after five innings. But they had a doubleheader Saturday, and one reliever, Craig Stammen, was already spent after cleaning up for Gio Gonzalez on Thursday.

So Strasburg jogged out for one more inning. He threw his fastball in the low-to-mid 90s. Freeman led off with a single, and McCann followed by blasting a 92-mph fastball over the scoreboard in right field. Uggla ripped another single and Janish smoked a lineout to right.

One pitch after Strasburg bounced a change-up, pinch-hitter Eric Hinske drilled a 94-mph fastball off the top of the right field fence, so close to being a home run that umpires reviewed the hit before ruling it a double.

“For the most, I threw pretty well,” Strasburg said. “It’s tough. I left a couple pitches up, and they’re hitting them. I can’t stress about the last inning too much.”

As the Nationals retreated to their quiet clubhouse, they had to figure out how to move on quickly. After playing for 4 hours 21 minutes, they would return to the locker room in less than 12 hours. Clippard said the rapid turnaround would help ease the sting. They will find out if their brutal loss lingers.

“That’s not the makeup of this ballclub,” Johnson said. “Nothing but gamers over there. We knew it wasn’t going to be easy.”

But, he knew, it didn’t have to be so hard.