DeGrom was injured while striking out swinging in the third inning. He returned to the dugout and told manager Mickey Callaway his arm hurt but he wanted to keep pitching. DeGrom pitched smoothly through the heart of Atlanta's order in the fourth, but then told the staff his bicep was sore and left for the clubhouse after 46 pitches. The Mets' telecast showed a frustrated deGrom returning to the clubhouse with his glove hand on his head.
The ace was sent for an MRI, and the team expects to get results Thursday. Callaway said he has no idea how long deGrom could be out.
"We're not quite sure what the deal is," Callaway said. "We won't have any information until tomorrow."
"I'm sure I won't sleep very good," he added.
Callaway, the former pitching coach with the Cleveland Indians, said he has never had a pitcher suffer a hyperextended elbow.
"I've always been in the American League," he said. "I'd rather them not hit."
Callaway said Corey Oswalt and Matt Harvey could be candidates to fill deGrom's rotation spot if he has to miss time.
DeGrom upped his scoreless innings streak to 18⅓, and he seemed in control against the Braves.
He chewed up Atlanta early, striking out Ozzie Albies on four pitches to lead off, using six more pitches to finish up the first inning and cruising through four innings without incident, with two hits and six strikeouts. He struck out four straight at one point and lowered his ERA to 1.87.
The Associated Press contributed to this report.