Oscar winner Kate Winslet has heaped praise on Michael Fassbender, claiming he is one of the hardest-working actors in the business. The two worked together on the upcoming Steve Jobs biopic, directed by Danny Boyle.

The Kerryman stars as the Apple founder, while Winslet plays Joanna Hoffman, who worked closely with Jobs from the early days of Apple Computers.

"I want to make sure you hear me loud and clear: I have never, ever seen an actor work so hard," she said.  "His work ethic is un-f**king believable, to the point where I would worry about him. He had 182 pages of dialogue. He was on every single page. It was like learning Hamlet times two," she added.

The powerful script was written by Aaron Sorkin, known for penning shows like the West Wing, and the movie is written in three acts. While Winslet was impressed by his ability to learn lines, Fassbender said it takes him a while to perfect the dialogue.

"It honestly takes me longer than the average person would," Fassbender said.

"I just read it over and over again and kind of go crazy and keep reading it and go a little crazier and just keep reading it."

Steve Jobs star Michael Fassbender has praised co-star Kate Winslet for being a "great partner" in making the film, but he also admitted to being intimidated by the Oscar winner early on in the process.

As Winslet hails from the U.K. and Fassbender is from Germany, they both had to master American accents which, according to Fassbender, Winslet did almost immediately.

The film has been getting rave reviews and Fassbender is pleased that his performance is garnering Oscar buzz.

The 38-year-old was previously nominated for his role in 12 Years a Slave.

Steve Jobs, which also stars Seth Rogen and Jeff Daniels, will open in cinemas on November 13.