Rob Gronkowski is more likely to continue his career in 2018 than retire at the age of 28.

Sources say Gronkowski is "pretty certain" he'll play as long as Tom Brady remains with the Patriots.

Lingering frustrations remain between Gronkowski and head coach Bill Belichick, along with others in the Patriots organization, according to sources close to each side. Gronkowski has suffered not only from physical injuries but the mental fatigue of New England's high-strug culture.

Gronkowski began to consider retirement due to the physical toll of the 2017 season.