The Washington Nationals’ decision to shut down Stephen Strasburg has consumed the baseball world for months, and Friday night, as the countdown whittled to one start, it may have consumed Strasburg himself.

In what the Nationals planned to be his final appearance at Nationals Park and penultimate start of the season, Strasburg surrendered five runs over three ragged innings in a 9-7, 10-inning loss to the Miami Marlins. He allowed six hits, three walks and two homers to the same lineup that battered him two starts before.

The Nationals overcame a four-run deficit to force extra innings, a rally capped by Michael Morse’s solo homer in the eighth. They nearly erased the three-run lead the Marlins took in the 10th inning against closer Tyler Clippard. But afterward, with their lead in the National League East sliced to 61 / 2 games, Manager Davey Johnson worried more about his ace than he celebrated his team’s effort.

Strasburg became so concerned about letting teammates down he had trouble sleeping in recent nights, Johnson said. Strasburg still rejected the idea that anything but a poorly located fastball undid him. Johnson sensed otherwise.

“To be honest with you, I think he was thinking too much about the decision” to end his season early, Johnson said. “And he kind of wore it. . . .But that’s the way it is. I think he wasn’t focused as much on the game as he was on the impending shutdown. Just the way I read it.”

The shortest start of Strasburg’s season pushed his total to 1591 / 3 innings. Johnson had announced Strasburg would make his final start Sept. 12 in New York against the Mets. Asked if the short outing could change the Nationals’ plans for their ace, Johnson gave a cryptic answer.

“It might,” Johnson said, and then he left his news conference.

Strasburg kept to himself whether he would campaign to have his season extended past Wednesday. “”I’m going to focus on the next start,” he said.

Johnson said he would speak with Strasburg about his focus between now and Wednesday. For his part, Strasburg insisted he had merely had a bad night Friday.

”I think as a professional you want to go out there and give it everything you have, every single time out,” he said. “So that’s what I want to go out there and do. Unfortunately, it wasn’t good enough.”

The memories from his planned final appearance in Washington this season will almost all be bad for Strasburg. The crowd of 28,533 showered him with an ovation as he walked in from the bullpen and, when his name was announced, the cheers were both an acknowledgment and audible hope for a special night.

Strasburg’s full performance, then, was an anticlimax. He walked the game’s first batter. He surrendered two home runs, both on fastballs thrown to the center of the strike zone.

He threw 67 pitches. Remove two outs by Jacob Turner, the opposing starting pitcher, and Miami hitters went 6 for 13 with two three walks and two homers against him.

“He’s not going to throw a no-hitter every single time,” third baseman Ryan Zimmerman said. “He’s human. Nobody has a good time every time out. . . . He’s been the same since Day One. I think he had a bad day, just like every pitcher has a bad day every now and then.”

On Aug. 28, two starts before his outing Friday, the Marlins tuned up Strasburg in Miami. Strasburg allowed a career-high nine hits and seven runs, five of them earned. Marlins batters had ambushed him, hacking at his first pitches, and Strasburg realized he never adjusted by throwing fewer sinking fastballs early in the count.

“I know he’s fully aware of the bushwhacking he got last time,” Johnson said before the game. “They may not be as comfortable up there.”

By all appearances, they were. Three of the first four Marlins batters reached base, with Giancarlo Stanton lacing an RBI double. In the second, catcher Rob Brantly hit a moon-shot homer on a 95-mph fastball right down the middle. Stanton hit another homer in the third, blasting a 97-mph heater down the chute.

“I didn’t command the fastball,” Strasburg said. “I kept getting behind in the counts. And when I keep falling behind, I wasn’t able to use my other pitches effectively, and they teed off on me a little bit.”

His execution, not his mind-set, had led to the Marlins’ barrage. But his mind-set could have affected his execution.

“Command and focus kind of go hand-in-hand,” pitching coach Steve McCatty said. “Whether you want to say his command was off, well, there’s usually a reason why. So maybe focus could’ve been a little better.”

“He’s a part of this team,” Johnson said of Strasburg before the game. “He wants to be helping until the end. He doesn’t want to let the team down. That’s the emotional part, the professional part on his side. He’s willing to risk it being his last year to have that. I understand that. But it’s our job to make sure it’s not another Mark Prior or anything like that.”

Strasburg’s rocky outing left the Nationals down, 6-2, after six innings. Left-hander Zach Duke, making his first major league appearance since 2011, held the Marlins at bay for four one-run innings.

The Nationals began their comeback with three runs against the Marlins’ bullpen in the seventh. Morse completed it with a solo homer in the eighth inning, crushing A.J. Ramos’s 96-mph fastball into the right-center field seats to tie it 6. Bryce Harper cut down the go-ahead run at the plate in the ninth inning with a cannon throw from center field, “as perfect as you can get,” Suzuki said.

But they couldn’t score in the ninth, and in the 10th, Clippard yielded a two-run triple to Jose Reyes and a sacrifice fly. With one run in, the Nationals loaded the bases with one out off Marlins sidewinding closer Steve Cishek, but Roger Bernadina and Jayson Werth struck out to end the game.

The Nationals could not get Strasburg off the hook, and he had four days before, most likely, the final day of his season.

“Let it go and focus on the next one,” Strasburg said.

Even if there may only be one more next one left.