Robert De Niro had to convince Sylvester Stallone to star in their upcoming boxing film Grudge Match.

Stallone was apprehensive about starring in another boxing film in case it damaged the Rocky legacy that he is so proud of.

He explained to Empire that De Niro talked him into it, ''I had a great many reservations. He's relentless, don't let that quiet demeanour fool you. I was being precious about Rocky. I was very happy with the way it ended.

"But Bobby just kept hammering away. Finally, he made sense. I talked to my wife and said, 'Maybe it would be interesting to take the good baggage and pit it against another iconic character because it'll never happen again'."

De Niro earned an Academy Award for his portrayal of boxer Jake La Motta in Raging Bull in 1980 and he added that he only thought the film would work if it was himself and Stallone, "I was ready to go, but I knew the only way it would work was the two of us. I called him up and said, 'Let's try it'."

Grudge Match is set to hit cinemas on January 24.