Tom Cruise gave newcomer Danika Yarosh a dictionary during her first week on the set of new movie Jack Reacher: Never Go Back, the rookie actress said.
The 18-year-old, appearing in her first major film role as tearaway Sam Dayton, said the veteran Top Gun star took her "under his wing" on set.
Speaking at the film's European premiere, the American teenager said Tom also "took it upon himself" to be her teacher - and gave her tips on how to execute stunts without getting hurt.
She told the Press Association: "The first week on set he actually gave me this big dictionary with everything I ever wanted to know about film.
"It was a dictionary specific for film, so if I was ever on set and something was said that I didn't understand but didn't want to ask, I could just look it up no problem.
"He taught me about everyone on set, what their roles were, and how they contributed to the film."
She added: "He taught me all about stunts so if he was ever doing a big stunt that I wasn't part of he had me sit next to the camera so I could watch him do it in real life and see how you see it on camera.
"It was a masterclass from the best."
Tom spent over an hour on the red carpet in London's Leicester Square, meeting fans and speaking to press, having flown in from Los Angeles earlier that day.
Asked if he had any plans to reduce the amount of stunts in future films, he said: "I'll be running till the very last day.
"In each one (film) I'm just learning a new challenge.
"I like studying, I'm always studying, pushing myself to find new stuff. I kind of find something and make it part of the movie.
"I just do it, it's who I am and part of my life. I've trained my whole life and I just apply it to movies - I'm always learning a new skill."
Jack Reacher: Never Look Back is released today.