TMZ Sports Show: Rob Gronkowski -- 'Jacked' for a Comeback

Rob Gronkowski ... aka GRONK ... is back! We had a hysterical run-in with the Patriots star while he was training in L.A. -- and while he definitely looks "jacked" ... will he be ready to go next season?

Plus, soccer star Cristiano Ronaldo tries to upstage his supermodel GF Irina Shayk by jumping into a a super-tight pair of jeans! We know they look awesome on Irina ... but Cristiano??