A source has told NFL.com that Rob Gronkowski is likely to miss the New England Patriots' opening game of the 2013 NFL season.
The tight end underwent a back operation earlier this year that was expected to keep him out of action until September.
The website now reports that the 24-year-old is "doubtful" for the AFC East champions' week one clash with the Buffalo Bills.
Gronkowski scored 11 touchdowns for the Patriots in 2012.