Leonardo DiCaprio says Jonah Hill "changed the dynamic" of 'The Wolf of Wall Street'.
The actor praised his co-star in the movie - which has five nominations at tonight's (02.03.14) awards, including Best Actor for himself, and Best Supporting Actor for Jonah - because of the way he works on set.
Speaking to ABC news on the red carpet, he said: "Martin [Scorsese, director] always looks for people that feel like they are the character and the second I met Jonah he said, 'I know who this guy is, I know who these people are, there's no-one that can play this role except for me.'
And he met with Marty and in two hours he gave him the role. "It was unbelievably to work with an actor like that who brings so much to the table, he really improvised every single day and changed the dynamic of our shoot and changed the narrative ultimately, and he's become a great friend in the process."
Leonardo added he spent many years getting the movie into production and became "obsessed" with, Jordan Belfort, the disgraced New York stockbroker who wrote the novel the movie is based on.
He added: "It was really a six or seven year process to get this made since I optioned the book, and I became completely obsessed with Jordan Belfort's novel. It's a movie about our times and wealth and this idealistic image we have with money, and I wanted to put this culture up on the big screen, and I knew only Martin Scorsese could be the director to bring the sort humanity to this that it needs.
"There has only been two films in my life that I've fought tooth and nail to put up on the screen and both of them were directed by Marty, one was the Aviator and the other was this. So I've very honoured to be here tonight and to have our film acknowledged in this way."