Hollywood hardman Sylvester Stallone shocked the cast and crew of his new boxing movie Creed by posing brain-busting riddles and quoting French philosopher Voltaire on set.

The veteran action movie star shed his tough-guy image and showed off his intellectual side while shooting the latest installment of his Rocky franchise, and it left leading actress Tessa Thompson suitably impressed.

She tells New York Post gossip column Page Six, "He’s kind of an encyclopaedia of literature and film knowledge. He’ll, like, sit and quote Voltaire. He’s constantly cracking jokes, he’s really fond of riddles... He’s always keeping the energy light and telling anecdotes about the other (Rocky films) they’ve made.”