DiCaprio and Maguire star in Baz Luhrmann's adaptation of F Scott Fitzgerald's "The Great Gatsby" as Jay Gatsby and his friend Nick Carraway.
The "Titanic" star, 38, explained that he arranged for his long-time friend to audition for the role after he secured his own part in the movie.
"Tobey is great at, you know what he's great at... He will find a way to win, and that's what I've seen happen in his life, too. I've seen Tobey, like Gatsby, say, 'This will happen for me'.