New York Mets ace Jacob deGrom, who left Tuesday's intrasquad game with back tightness, will undergo an MRI on Wednesday and is day to day, manager Luis Rojas told reporters on Wednesday.
The 2018 and 2019 National League Cy Young Award winner was removed from Tuesday's outing after only one inning, which calls his availability for the Mets' opener against the Atlanta Braves on July 24 into question.
DeGrom told reporters before the intrasquad game that he was aiming to throw around 85 pitches in order to be properly stretched out for the start of the delayed season.
DeGrom underwent elbow surgery near the end of the 2016 campaign but has been highly durable over the last three seasons.
The three-time NL All-Star's 622.1 innings pitched since 2017 rank second in the majors, trailing only Houston Astros ace Justin Verlander's 643.
The Mets are already without one of their top starters with Noah Syndergaard to miss the shortened season recovering from Tommy John surgery, and the rotation took another hit over the offseason when 11-game winner Zack Wheeler signed with NL East rivals the Philadelphia Phillies as a free agent.