Luke Wilson was left embarrassed when Lance Armstrong visited the set of his directorial debut The Wendell Baker Story - because the cycling champion first saw him shouting at elderly actors Harry Dean Stanton and Seymour Cassell.

Wilson co-directed The Wendell Baker Story with his brother Andrew and was angry with cult actors Stanton and Cassell for not knowing their lines.

But the 35-year-old was unaware Armstrong was on set when he lost his temper. He recalls, "I just thought they hadn't done their homework. I was talking to them the way I talk to a friend, and you forget that Harry Dean was almost 80, Seymour's 77. I was barking lines out to them. And they said, 'That's not the way we work.' And I was saying, 'Well, what the f--- do you want to do if you don't have the dialog memorized? We don't got time for this bulls---. And I glance over, and there's Lance Armstrong, the one day he decides to visit the set. This great champion, and he knows me as this guy that yells at old people."

-Luke Wilson Pictures