Sylvester Stallone has made a veritable movie industry out of his epic on screen boxing sagas, but in a recent Instagram post, Sly has revealed the one man who he felt was the worst boxer in the “whole universe” while making the 2013 sports comedy movie, Grudge Match.

Stallone’s portrayal of Rocky Balboa put him in the ring with some of film’s greatest athletes: From the late, great, Carl Weathers’ turn as Apollo Creed to the wrecking machine that was Dolph Lundgren’s Ivan Drago, the people’s champion even took on genuine boxers like Antonio Tarver, receiving genuinely painful punches from his on-screen opponents in the process. But in a new video posted to the actors Instagram account, Sly reveals that it was the Raging Bull star Robert De Niro who showed the least promise in the squared circle.

Sylvester Stallone names Robert De Niro as the worst movie boxer he’s worked with

The two titans of cinema were united in the sports comedy, Grudge Match and the plot saw the screen icons playing the roles of aging boxers who were past their glory days but were still fuelled by a bitter rivalry and an unwillingness to hang up the gloves. It is a genuinely funny movie and includes a great supporting cast including Kevin Hart and Kim Basinger, but it bombed at the box office, and while the movie is still definitely worth a stream, Stallone says that De Niro was no raging bull.

“… I thought, ah, he’s Raging Bull, he’s gonna come here, he’s gonna kick my butt, I’ve heard all these stories,” said Stallone. “He gets in (the ring) and I can tell his knees were shaking … he put his gloves on and kinda looks like lobster claws, so I said let’s move a little bit, and ‘oh my God!’ I said; ‘you’re a great actor, but you’re the worst boxer I’ve ever seen in the whole universe.”

In fairness, De Niro was 70 when the movie was released and well past his Raging Bull days. The machine that is Sylvester Stallone, however, was still fighting fit at 67. The Taxi Driver star responded to being told how awful he was in the ring by seeking help from the most successful movie boxer of all time: “… He kind of admitted it, \[saying] ‘I don’t know what to do, point me in the right direction,’” says Stallone. “And I said; I’ll do my best but I’m warning you, your Oscars aren’t gonna save you in here! So, keep punching Bobby.”

Grudge Match is not a movie that either man will likely be remembered for, but their friendship and comradery is clearly stronger than ever.