While Tom Brady was throwin' bombs to his new teammate, Antonio Brown ... Rob Gronkowski was busy ass-shakin' to some Backstreet Boys in an epic dance-off with his GF!!
The retired Patriots superstar is staying active on his NFL Sundays ... teaming up with his bikini model lady, Camille Kostek, for a public workout at the Boston Seaport with his family's Gronk Fitness business.
The workouts are great and all ... but we're 100% here for the hot couple getting down and GETTING IT to BSB's "Everybody (Backstreet's Back)" ... while the whole crowd cheers them on.
The Patriots didn't need Gronk in their 43-0 domination over the Miami Dolphins ... and Gronk sure as hell didn't need the Pats to have a good time, either.
Of course ... maybe the 30-year-old is using BSB to send us a message -- if Backstreet's back, does that mean Gronk could be coming back too??
As entertaining as it was to watch Rob on the field, this tames our Gronk appetite on Sundays. For now.