"I told him (De Niro), 'In here, your Oscars are not going to help you pal, you're in Rockyland," Stallone told Confidenti@l in an interview.
After making some good shots during the epic ring scene between 'The Rocky' and 'Raging Bull' of Hollywood fell down to which Stallone said to De Niro, "This is getting good, this is not a joke fight."
Stallone, 67, also admitted that the age aspect in the movie is also realistic.
'Grudge Match' is a story of two ageing boxing rivals coaxed out of retirement to fight one final bout - 30 years after their last match.
'Grudge Match' releases in India on January 10, next year.