Martinez (knee) had his rehab assignment shut down recently after he hyperextended his left shoulder on a swing, Justin Toscano of The Bergen Record reports.
Martinez exited Thursday's game at Triple-A Syracuse due to the injury, and he'll return to New York to be further evaluated. The 33-year-old appeared to be close to making his season debut after he missed the start of the year following offseason surgery to address a meniscus injury in his left knee, but it's not yet clear how his recent setback will impact his return timetable.