Wong's next film was not released for five years, as he underwent another long and difficult production on "The Grandmaster" (2013) – a biopic of the martial arts teacher Ip Man. The idea had occurred to him in 1999 but he did not commit to it until the completion of "My Blueberry Nights". Ip Man is a legendary figure in Hong Kong, known for training actor Bruce Lee in the art of Wing Chun, but Wong decided to focus on an earlier period of his life (1936–1956) that covered the turmoil of the Second Sino-Japanese War and World War II. He set out to make "a commercial and colourful film". After considerable research and preparation, filming began in 2009. Tony Leung Chui-wai rejoined Wong for their seventh film together, having spent 18 months being trained in Wing Chun, while Zhang Ziyi played Gong Er. The "gruelling" production lasted intermittently for three years, twice interrupted by Leung fracturing his arm, and is Wong's most expensive to date.