Chen is listed as having a strained right oblique, but he will be re-evaluated Monday in Baltimore.
Chen said he felt the discomfort while facing his last batter, Eduardo Escobar, in the bottom of the fifth inning, and it intensified on the final pitch.
Meanwhile, Jake Arrieta didn't make his scheduled start today with Triple-A Norfolk because of a tender right shoulder, according to manager Buck Showalter.
The shoulder apparently has bothered Arrieta for the past few days. He's had some trouble getting loose.
Showalter isn't sure whether Arrieta will only be pushed back a few days or skipped in the rotation. There's some concern in the organization, but not at a high level.
Arrieta may have been recalled today as an extra reliever if not for the shoulder issue. Showalter checked on him last night before the club decided to recall left-hander Mike Belfiore, who didn't pitch today.
And finally, Manny Machado is the first player under 21 years old to collect three straight three-hit games since the Pirates' Rennie Stennett on Sept. 3-5, 1971, according to Elias.
Here's how Chen, speaking through his interpreter, described what happened to him in the fifth inning that led to his removal from the game:
"I can tell in the fifth inning, the last batter, (Eduardo) Escobar, after two strikes I was just having a weird feeling and I just tried to be strong and finish out that inning. And the last pitch, I finished the delivery and started feeling, maybe that's a cramp on me. I don't know. We'll see what happens tomorrow. I hope it's just a cramp.
"It's never happened to me before, and I can tell I had a really good first four innings and I definitely feel good physically. Unfortunately, in the fifth inning, I don't know what happened.
"It's not that serious to me. I think it's just a cramp, and we'll see what's going to happen tomorrow. We will re-evaluate tomorrow and hopefully it's just a cramp."
Asked to describe the pain, Chen said, "I wish I can tell you what kind of feeling I had. It's just kind of like a soreness. It's just a cramp.
"I really don't know what kind of feeling of that because it's only one pitch and it was the last pitch. And the groundball out and everything happened, and I cannot tell what happened. But tomorrow we will have to re-evaluate again so the result will come out tomorrow."
Chen added that he wasn't in pain after the game. He felt fine while standing at his locker talking to reporters.
As for his outing, Chen said he had trouble with his command early, "but (Chris) Snyder helped me a lot."
"On the other hand, Nicky really helped me," Chen added. "Markakis had a really nice play on the throw to second, and that really helped me. After those couple pitches, my feeling was back and everything was on track. I thought, I really hope I can go deep today, and it just did not happen today."