Drew Pomeranz left his exhibition start one inning earlier than expected on Sunday due to left triceps tightness.
Pomeranz first developed the tightness in the first inning against the Minnesota Twins and it persisted into the second frame. He threw 47 pitches and didn't come out for a third scheduled inning.
The left-hander told reporters he didn't think the injury was serious, but the Boston Red Sox will be careful. Pomeranz experienced left elbow/forearm stiffness late last season and received a stem-cell injection over the winter.
There are also injury concerns surrounding David Price entering the season.