Strasburg went six innings, allowing two earned runs on six hits with four walks and eight strikeouts. He struggled with his fastball command throughout the game but managed to limit the damage.
"That was a tough one, but the main thing, I was a little concerned about Strasburg," Johnson said. "He always has a tendency to shake his right arm, and him being wild, I talked to (pitching coach Steve McCatty) and (said) 'Have you talked to him? Because he doesn't look right to me.' He was still throwing the ball real hard, but I told him after he went out for the sixth, 'I'll get you out of there, get you a win.'
"He was in there with the doctor. He's got a little tightness, I think in his forearm. So they're gonna put him on some medication. He'll get a report from the doctor. But that was a bad thing in the game. Still throwing good, but his command was way off, so I knew something was off."
Strasburg brushed off questions about his health after the game, but didn't directly address anything about his forearm.
"I felt good out there today," he said. "Just battling through commanding the fastball, commanding off-speed, it was just one of those days."
Strasburg was shaking his arm throughout the game, and was seen rubbing his forearm in the sixth inning. He often tends to shake his arm during outings, though, and said it's not unusual for other pitchers to do the same.
"Yeah just trying to stay loose and stuff," he said. "Look at any pitcher. It's not like they're standing out there like robots. Everybody's going to be trying to stay loose."
Johnson said that it was too early at this point to determine whether Strasburg would be able to make his next start. Strasburg, on the other hand, has no plans of getting his turn in the rotation skipped.
"I'm not missing my next start," Strasburg said tersely. "I'll tell you right now."
Given Strasburg's injury history - he had Tommy John surgery in September of 2010 - if the right-hander is dealing with any elbow or forearm issues, the Nationals would likely proceed with extreme caution.
Johnson said that Strasburg didn't mention anything about any discomfort during the game, and catcher Kurt Suzuki said he didn't get any word from Strasburg that he was feeling less than full-strength health-wise.
"He didn't complain about anything," Johnson said. "Of course, he was irritable, but he can be irritable during a ballgame. I was really concerned."
Strasburg struggled with his command from the get-go tonight, throwing first-pitch strikes to just one of the five hitters he faced in the first inning. His four walks ties a season high.
"I smoked the umpire (with a pitch) on the first AB," Strasburg said. "You don't want to go out there and do that. ... I was pulling the ball. Can't really say why I'm having a tough time right now in the first inning, but I am. Just got to keep grinding and I'll figure it out."
As far as Johnson's concerned, Strasburg's control issues today were a direct result of the forearm tightness.
"But hopefully it's nothing more than maybe a little tired arm or something," Johnson said. "... He's a lot of times shaking his elbow to stay loose, but this was more than I've seen, more frequently. And that coupled with the ball going everywhere, that's why I cut him a little short.
"That overrides everything (that happened in the game). Hopefully he's gonna be all right. But we're just going to have to wait and see."