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Stephen Strasburg exited the Nationals’ 3-2 victory over the Atlanta Braves after two innings with a right oblique strain and took a flight back to Washington late Friday night for a further examination from Nationals team physician Dr. Wiemi Douoguih. Strasburg tried to convince Manager Davey Johnson to let him continue and hopes to make his next starts, but oblique strains tend to linger and can sideline pitchers for up to six weeks.

“It’s something where, the last few starts I’d feel it warming up,” Strasburg said. “I’d go out there and I wouldn’t feel anything. Tonight, it was more kind of like the reverse. I felt really good in the bullpen. I threw a couple pitches in there, and it started to tighten up. I felt it more and more. Nothing I could do about it. I’m kind of frustrated.”

Johnson said the Nationals had not planned to place Strasburg on the disabled list until after a further diagnosis, yet  after midnight Class AAA Syracuse pitcher Erik Davis, a right-hander on the 40-man roster, revealed on his Twitter account he had been promoted to the majors. It’s possible Davis will be coming up for Bryce Harper, whom Johnson said earlier could land on the DL with left knee bursitis.

“He wanted to continue,” Johnson said of Strasburg. “He was wincing and in a whole lot of pain. I was not so much worried about his back as I was worried about his arm. Anytime you have something like that, you worry about putting more stress on your arm.”

Strasburg’s oblique was “nagging” him for the past several starts, he said, but he had always been able to pitch through it – it would loosen up as his starts went on. Word of Strasburg’s ailment had spread to long reliever Craig Stammen, who would need be ready in case of a serious injury, and bullpen catcher Nilson Robledo. In the first inning, in a prescient if not factually accurate statement, Robledo told Stammen, “Be ready. His shoulder’s hurting.”

“He’s throwing 98,” Stammen replied. “His shoulder’s not hurting.”

Then Stammen started seeing Strasbrug grimace.

“The second inning, you could just tell he was laboring a little bit,” Stammen said. “He just didn’t look the same. So, I guess I kind of got ready. I was praying he could keep going.”

Strasburg appeared uncomfortable as he pitched through his second inning, which began with a deep home run by Freddie Freeman. Strasburg struck out the next hitter, Evan Gattis, as he twice hit 98 miles per hour with his fastball.

In the next at-bat, against Brian McCann, Strasburg threw two consecutive change-ups, the pitch most difficult on his arm- it was the pitch he threw in 2010 when his ulnar collateral ligament snapped. On his next pitch to McCann, his fastball dipped to 94.

“It was more so after I threw the pitch,” Strasburg said. “I think that was kind of affecting the way I was finishing everything. It’s kind of hard when you know what you’re going to feel after you throw the pitch. You just kind of go out there and try and trick your mind, thinking it’s not going to happen.”

Strasburg threw five more fastballs, all of them hovering between 93 and 95. After several pitches, Strasburg had appeared to roll his right shoulder and grimace. McCann would ground out, and then Strasburg struck out Uggla with a curveball to end the inning.

“He was wiggling,” catcher Kurt Suzuki said. “I had to double-pump like every pitch because I couldn’t throw the ball back to him. So you knew something was physically wrong with him.”

In the dugout, Johnson, pitching coach Steve McCatty and trainer Lee Kuntz approached. Strasburg wanted to pitch, but Johnson would not allow it.

“There’s a lot of times you go out there and you don’t feel 100 percent,” Strasburg said. “You just go out there and gut through it. It was tough, because he kind of had his mind made up. As much as I was saying, as much as I was trying to convince him, he didn’t want me to go out there.”

Strasburg’s injury adds to a calamitous first third of the season for the Nationals. They sat at 27-27 entering the weekend and have played chunks of the year without Bryce Harper (who missed his fifth straight game Friday night), Jayson Werth, Ryan Zimmerman, Wilson Ramos and Ross Detwiler.

Detwiler has been on the DL since May 16 with an oblique strain, which is similar to Strasburg’s, Johnson said. Detwiler will miss his turn again Sunday, meaning he will miss close to a month, at least, after injuring his oblique. Unlike Strasburg, Detwiler hurt the oblique on his non-throwing side, but Johnson said that would not make much of a difference.

“Well he was complaining of discomfort warming up and it was more severe than it was the last time out,” Johnson said. “He’s a gamer. He wanted to continue. But something like that, and I saw him wincing every throw he made, and even Suzuki made the sign, you know, like, it’s not real good. But I’m not gonna take a chance with his arm. That’s the main concern. The side will heal, but when you try to do too much out there, it’s dangerous. So he was not going to continue.”

On Friday night, before he saw Douoguih, Strasburg felt confident he would not need to land on the disabled list.

“Honestly, I could have gone out there and kept pitching,” Strasburg said. “My command wasn’t there, but I think I definitely could have pitched through it. But, you know, Davey didn’t want to take the chance. You just got to be proactive about it, get the treatment. Hopefully, I should be able to make the next start.”

The Nationals have an off day in their schedule, which could help Strasburg. The Nationals could skip him once in the rotation and bring him back June 8 without any of their starters pitching on short rest. That, though, could be optimistic based on how long oblique injuries tend to sideline pitchers. Strasburg’s may be less severe than a typical oblique strain, but the injury typical sidelines pitchers an average of five weeks.

“He had a little bit of symptoms but it loosened up for him,” Johnson said. “But he wasn’t wincing like he was today. Let’s just hope this settles down and he’s able to continue throwing. But our doctors will let us know. It’s the same thing. It’s not the lower back. It’s more on the side.”

The Nationals’ pitching depth, a weakness to start the year, was depleted this week when veteran right-hander Chris Young went on the disabled list at Class AAA Syracuse. Nate Karns, a 25-year-old rookie with nine minor league starts above Class A, will make his second career start Sunday in place of Detwiler. Stammen or Zach Duke, the Nationals’ dual long relievers, could be options if Strasburg misses a start.

The Nationals have closely monitored Strasburg’s health since they drafted him with the first overall pick in 2009. Strasburg underwent Tommy John elbow ligament replacement surgery during his rookie year in 2010. Last season, General Manager Mike Rizzo controversially shut down Strasburg in September as the Nationals headed into the playoffs.

Earlier this season, Strasburg raised fleeting concerns about the health of his arm during a start in Atlanta. After he frequently shook his right arm on April 29 start, Johnson said Strasburg was feeling tightness in his shoulder. Strasburg and Rizzo both insisted Strasburg was fine, and before Friday night he had shown no sign of wear.

Entering Friday, Strasburg had reeled off one of the best stretches of his career. He twice pitched into the eighth inning – which he had never previously done – and allowed three earned runs in 23 innings across three starts. In those three outings, as his season ERA lowered to 2.54, he threw 117, 108 and 112 pitches.

“He told me about it,” Stammen said. “He’s just been having trouble getting loose or whatever but, like, he’s been pitching good so, like, whatever. Hopefully it still hurts. But maybe not, I don’t know.”

Then came Friday, the biggest scare of a dreary season. Strasburg threw only 37 pitches before he left, headed to visit team doctor Wiemi Douoguih. And then Stammen stood up in the bullpen, the first step in a performance that salvaged an otherwise unsettling night.

“It kind of puts a wrench into it,” Strasburg said. “You got to take care of the body. The biggest thing is figuring out what’s going on. Get to the root of the problem, fix it, get back out there.”