“I hope it’s nothing serious, but we’re going to send him to go get an MRI and make sure it’s nothing serious,” Johnson said. “We don’t want to take a chance of aggravating that. I don’t have a good feeling, I mean, he’s had three days off, had treatment so it could calm down the inflammation – we thought it was inflammation. Hopefully it’s nothing serious. We’ll know after they take the MRI.”

After he rested the previous three days, Zimmerman expected to play tonight as the Nationals begin a six-game West Coast swing in San Diego. He underwent an X-ray, which determined that he did not have shoulder inflammation, as originally thought, but rather a sprained AC joint. Zimmerman felt “100 percent” while throwing today, but his shoulder hurt when he made contact while swinging.

“There’s nothing wrong with the shoulder,” Zimmerman said. “I can throw. Everything felt fine. It’s just still a little sore when I swing. It’s like a jammed finger or a sprained ankle, I guess is the best way to explain it. Except it’s on my shoulder. If you sprain your ankle, you can tape it up and play through it. Obviously, you can’t tape your shoulder.

“It feels better today than it did two days ago. That’s a good thing. It’s just one of those frustrating things where unfortunately, there’s nothing you can really do for your shoulder. But there’s nothing structurally wrong.”

Still, the Nationals will make certain by sending Zimmerman for an MRI, and they should have the results back later tonight. After he threw without pain or restriction, Zimmerman feels confident he did not tear his labrum or rotator cuff. But if he strained his AC joint, Johnson said, Zimmerman could miss a week or more, which would necessitate a disabled list stay.

“I certainly don’t want to think about anything over a week or 10 days,” Johnson said. “Just have to wait until I hear from that report tonight around 9. I’ve got my fingers crossed.”

The Nationals rank 24th in runs scored per game without Morse, and without Zimmerman, in the lineup. Despite his slow start, they would absorb an even greater hit. Zimmerman said he didn’t expect to need time on the disabled list.

“I don’t think it should be,” Zimmerman said. “With how much it’s gotten better the last couple days, it’s just going to be a matter of whether or whenever I can hit without feeling it. It’s not going to be smart to try and go do something through that, to play with that stuff for so long. To take however many it’s going to take to get better, that’s definitely the smart play.

Zimmerman jammed his shoulder while making several diving plays over the Nationals’ homestand and also leaping into home plate trying to score a run – “the fourth-and-goal pylon dive,” he called it. Zimmerman is not certain which play, precisely, caused the damage.

Last year, Zimmerman missed roughly 60 games after undergoing surgery to repair a torn abdominal muscle. In February, Zimmerman signed a six-year, $100 million contract extension.

For tonight, Johnson played rookie Stephen Lombardozzi at third base and moved Mark DeRosa, who is 3 for 30 this season, into the third spot in the order. Johnson prefers to “slot” one player into the vacant spot in the order rather than switch up the whole order.

His real preference, though, would be to receive good news on Zimmerman’s MRI and pencil his best player into the lineup again in a day or two.

“We missed him a lot last year and we’re counting on him heavy this year,” Johnson said. “That’s why we’re probably being a little overcautious but he did hit and he did throw well but that’s not something we want to aggravate and make it longer. I’m already missing my four-hole hitter. I don’t need to miss my three-hole hitter.”