Stephen Strasburg allows one run and two hits and strikes out nine in seven innings to improve to 12-0 on the season for the Nationals. (Mike Stobe/Getty Images)

Stephen Strasburg will not pitch in the All-Star Game next week so he can pitch like this, powerfully and assuredly, into October. His Washington Nationals need seven-inning, two-hit, one-run starts like the one he compiled Friday night to fend off the New York Mets in the National League East. They need the man they signed to anchor the top of their rotation for the next seven years to match aces with zeros to give them a chance against the best.

Strasburg outpitched ailing Noah Syndergaard on Friday night at Citi Field in a 3-1 Nationals win. He will reach the all-star break unbeaten, the first National League starter to begin a season 12-0 since 1912. His Nationals are four games up in the National League East.

Because the Nationals need Strasburg to finish this season as well as it has begun, some combination of him, Manager Dusty Baker and General Manager Mike Rizzo decided pitching in the All-Star Game represented too much of a risk.

Hometown fans will have to do without the ace they watched grow from a gawky high schooler to a highly touted college prospect at San Diego State. Important as that game may be to the more sentimental San Diegans, the games the Nationals will play in the months to come mean more to those paying him $175 million over the next seven years. The 27-year-old spent too much of the past few seasons fending off upper-back trouble that never seemed to leave him worry-free. Better safe than sorry, a meeting of the Nationals’ minds concluded.

“They came to me and said that was what they were thinking. In my head, I’m thinking I want to make up for the two starts I missed,” Strasburg said. “Hopefully will be ready to pitch the first game back and get the second half going right.”

Strasburg returned from this year’s upper back trouble Sunday. He threw 62/3 hitless innings in his first start back from the disabled list. His pitch count rose too quickly for him to chase a no-hitter that day. He picked up the pursuit in front of 35,000-plus Friday night.

Strasburg powered through the first few innings with a 97-mph fastball and whatever secondary pitches he needed, earning five strikeouts in the first three innings, landing his curveball for key strikes all the while. When No. 3 hitter Yoenis Cespedes left the game with an injury in the top of the fourth, taking one of the Mets’ best weapons with him, circumstances seemed to be aligning to give Strasburg a chance at history. By the time Syndergaard departed with what was reported as “arm fatigue” in the top of the fifth, Strasburg had not allowed a hit in 102/3 innings since returning from the DL.

“He was outstanding,” Baker said. “And he went as far as he could go.”

Then he allowed one. Asdrubal Cabrera hit a 3-2 cutter/slider hybrid out to right to end the no-hitter and the shutout. Brandon Nimmo singled, too. Strasburg took his time, heading to the back of the mound between pitches before staring in, settling as the crowd came back to life. He pitched out of that inning. He struck out two more men in the sixth, then pushed through close calls that went against him and a flurry of Mets foul balls to survive a a 23-pitch seventh.

“That’s what aces do,” Baker said. “They finish. He’s matured, big time. Aces don’t depend on the bullpen or somebody else to do their job. He got his 12th win because of it.”

Baker had many lineup options when Trea Turner and Michael A. Taylor arrived to fill out his bench Friday afternoon. With Ryan Zimmerman on the disabled list with a strained left ribcage, Baker could have moved Daniel Murphy to first base and put Turner at second, but Baker chose Clint Robinson to play first instead.

Robinson entered the day hitting .218 with the third-fewest at-bats on the team, a statistic that no doubt troubled the self-described “panicker” who has a tendency to tinker. Given the extra hours afforded those who do not play every day, panicking and tinkering become agonizing tendencies. But given the start in Zimmerman’s place Thursday night, Robinson homered. Starting again against Syndergaard on Friday, Robinson hit a line drive home run to right field to give the Nationals a 2-0 lead. Ultimately, that was the decisive blow.

“Feels good,” Robinson said. “That’s a big game that we needed to win.”

An inning later, Murphy doubled into the gap in left-center field to drive home Jayson Werth with the Nationals’ third run. He hit a 98-mph fastball like he was working on driving the ball that way, with that quiet, deliberate swing responsible for the .345 average that has led the National League for most of the season. It was his 15th RBI against the Mets in his first 42 at-bats against them this season. Fans at Citi Field cheered Murphy when he first returned in May. Fans boo him now because, as of Friday night, he is hitting .409 against his former team this season.

So by the bottom of the third inning, the Nationals had given Strasburg as big a lead as any starter could hope for against Syndergaard. They did not get a hit after he left, which left the bullpen little margin for error. Blake Treinen got out of a first-and-third jam with one out in the eighth by getting Juan Lagares to ground into an inning-ending double play. Treinen, polite and mild-mannered, pumped his fist and roared off the mound because a lead that nearly got away did not for the moment. Robinson said he had never seen Treinen so pumped up.

“Our whole team had an emotion outburst,” Baker said. “. . . That’s as exciting as I’ve seen him. Boy, we really needed it. Those Mets, they don’t give up. They were threatening, and we ended their threat.”

Jonathan Papelbon pitched the ninth and earned his 18th save, so Strasburg got another win. The Nationals are 19-1 in his past 20 starts. They need more of these outings from him in September and October, so they will protect him in July.