Mastrobuoni will return to Mariners camp after suffering a calf injury during Team Italy's win over Team USA in the World Baseball Classic on Tuesday, Bob Nightengale of USA Today reports.
The severity of Mastrobuoni's injury will likely be revealed once the Mariners' medical staff gets a chance to look at him. The 30-year-old infielder had been having a strong spring before his injury, going 4-for-15 with a grand slam through seven Cactus League games, and he also went 2-for-3 with a double and an RBI with Team Italy.