That's when we'll know if the Patriots tight end needs a fourth surgery on his left forearm, ESPN.com reported, citing sources.
Doctors are waiting in hopes that an infection in Gronk's arm has cleared. They still need to go in and insert another plate in his forearm. If the infection hasn't cleared and another surgery is needed, Gronkowski might not be ready for New England's Sept. 8 season opener in Buffalo.
According to ESPN.com, Gronkowski has been working in the offseason program and "looks great."
Gronkowski broke the forearm in Week 11 last season and re-injured it in the playoff win over Houston.