"I'm hoping for the best, that it is bone spurs," Beachy said, though a torn tendon that would require season-ending surgery is also a possibility.
Losing a pitcher whose 2.00 ERA leads the National League would be a major blow to the Braves, but manager Fredi Gonzalez is optimistic.
"I don't expect the worst," Gonzalez said. "I don't expect his season to be over. I'm expecting good news, just bone spurs, and we'll have him back in 15 or 20 days or close."
Beachy's optimism is more tempered.
"There was no pop," he said. "That is what everyone talks about, and I didn't have a pop. I'm holding on to that, I guess."
The Braves gave Beachy three extra days of rest after he'd felt soreness in his start prior to Saturday, and he experienced no problems while retiring the first 11 Orioles.
But the 25-year-old bounced two curveballs to Chris Davis, then showed a loss of velocity on two fastballs and ultimately walked him. Shortly after calling catcher Brian McCann to the mound, Beachy headed off the field.
"I had no pain, no discomfort between my last start and this one," Beachy said. "I was hoping I'd come out and the pain would be gone, but it came back.
"It didn't feel good. It was gradual tightness. It wasn't worth trying to push through it."