The 47-year-old actor first dipped his toe in the film industry in the early 90s when he decided to leave his pop roots behind, but he has admitted he almost didn't get his big break in 'The Basketball Diaries' because of a war of words he had with the 'Titanic' star.
Speaking during a talk at the 2018 LEAP Foundation Conference in Los Angeles, California, on Tuesday (24.07.18), according to 'The Hollywood Reporter', Mark said: ''He didn't want me for the part, and I didn't think he was right for the part. We both had to really learn how to respect each other, and we earned it.''
Leonardo, 43, had made a name for himself in the industry by that point as he had already shot roles in TV shows 'Parenthood' and 'Growing Pains' and secured a best supporting actor Oscar nomination for the 1993 movie 'What's Eating Gilbert Grape'.
And he was seemingly furious that the then-music star had secured a part in the movie, which was about a teen basketball star's descent into drug addiction, because he didn't think he deserved a lead role due to his lack of experience.
However, once production started, Leonardo and Mark - who played Jim Carroll and Mickey respectively - managed to put their differences aside and get along.
Mark has since gone on to star in the likes of 'Ted', 'Lone Survivor', 'Mile 22' and 'Daddy's Home', and he's now deemed one of the highest paid actors in the world.
The Hollywood hunk recently said he owes a lot of his success to Mel Gibson because the director had advised him to take any and all work opportunities he could.
He said: ''He passed on a lot of movies, a lot of really good movies. And he told me, 'You should get it while there's time. Get it while it's there. If you've got an opportunity, work.'''