Washington Nationals right-hander Cade Cavalli left his Tuesday spring training start after 2⅔ innings.
Nationals manager Dave Martinez told reporters that Cavalli felt something behind his throwing elbow.
Cavalli, 24, is expected to have an MRI on Wednesday.
The Nationals selected Cavalli out of Oklahoma with the 22nd overall pick in the 2020 draft. Cavalli is regarded as one of the Nationals' top prospects.