SOME PEOPLE think on their feet. But for action director Yuen Wo-ping, ideas appear when he's on his back. 'I don't know why,' the world-class director says with a gentle smile. 'It's an old habit.' Yuen, who dreamed up the kicks and punches that graced international box-office hits The Matrix and Crouching Tiger, Hidden Dragon, may have dozed off while cogitating on-screen movements. But years after becoming a household name in Hong Kong with 50 films under his belt, he is finally making audiences around the world sit up and take notice. Born in Guangzhou in 1945, Yuen became involved in kung fu movies through his father, Simon Yuen Siu-tien, himself an actor and stuntman. As a young boy, Yuen would watch his father work and his interest in stunts and martial arts grew. Today, the 58-year-old - who splits his time between Britain and Hong Kong - is widely acknowledged as one of the world's best and most respected action choreographers. Master Yuen, as he is known to his colleagues, has just completed work on the Matrix sequels: The Matrix Reloaded, which premieres in America on May 15, and The Matrix Revolutions, which opens on November 7 (both should arrive in Hong Kong a week after the US dates). His primary task? Making sure stars Keanu Reeves and Carrie-Anne Moss made all the right moves. But making it look good is easier said than done. Revered by many as the inventor of artful torture, Yuen began training the actors in November 2000, about five months before the start of shooting. 'I had to teach them how to fight by opening their tendons and loosening their legs so their punches were strong and their kicks high,' he says. Having already worked with Reeves and Moss in the original Matrix, a film about a massive artificial intelligence system that has fooled humans into thinking their world is real, Yuen says his job this time was easier because they were familiar with some of his moves and requirements. But Yuen says the training was still taxing because fight scenes are different for each film, and the scenes and movements in the much-awaited sequels were particularly difficult. One of his younger brothers, Yuen Cheung-yan - who choreographed the three female stars in Charlie's Angels - was also part of the action choreography team for the Matrix sequels. Do the siblings work well together? Work is separate to family, the elder Yuen says. The first born of 10 children, he sees no difference between working with a friend, a brother or a complete stranger. Work is work and family is family, he says. Perhaps such an ethos is essential since filming is often a family affair. Eight of the Yuen siblings make their living through movies and martial arts and often work together (though not all at the same time) as actors, directors and stunt co-ordinators. This work philosophy also means he doesn't like to answer personal questions, such as those related to his late father. While Yuen was filming The Magnificent Butcher in 1979, his father died. Before that, father and son worked together regularly - Yuen Snr's last completed film, The Buddhist Fist (1979), was directed by his son. So after almost 40 years of movies and action choreography, is it hard to come up with new moves and sequences? 'It's difficult to call any of the moves new,' Yuen says. 'From when action movies first began, who knows how many thousands of action films have been made. Every person has two arms, two legs and a head, how do you design 'new' movements? 'The 'new' element arises from the fresh ideas in scripts, and to maximise the different props and the surrounding environment, so the audience feels and experiences different emotions and thoughts from watching the scenes.' Yuen's creativity in making use of the movies' settings are particularly evident in scenes such as the clash between Zhang Ziyi and Chow Yun-fat atop the bamboo forests in 2000's Crouching Tiger and Michelle Yeoh Choo Kheng's balancing act with a plate of tofu while thrashing a brutal boxer in Wing Chun (1994). The director seems able to see potential in everything. A big part of the Matrix sequels is filmed in Sydney at a location he liked because of its close proximity to Chinatown. ('As soon as we finished work we could just take a few steps to Chinatown and eat.') There, Yuen oversaw fighting scenes involving more than 100 people at a time. One scene took six weeks to film, he says. The sheer size of the scenes sets the sequels apart from the original, where combat was mostly one-on-one. The large number of people involved also made Yuen's job more difficult. Asked who on the set he enjoyed working with most, Yuen says he got on particularly well with Reeves. 'Maybe because he was the main character and we spent so much time together, but we seemed to understand each other,' says Yuen, adding that the young actor was a perfectionist. But did Yuen - who does not speak English - have difficulties communicating ideas to Reeves? 'Movements are universal, something that everyone understands,' Yuen says, adding that to him, perfect moves are a way of communicating. 'It's not limited to regions or language.' MATRIX FACTS ? The two Matrix sequels, The Matrix Reloaded and The Matrix Revolutions, have cost more than US$300 million (HK$2.4 billion) to make. ? Trailers for the sequels, first posted on the Internet last May, were downloaded two million times in the first 72 hours. ? Bullet time, the trademark special effects trick in The Matrix, in which the camera spins 360 degrees around an image, has since featured in Crouching Tiger, Hidden Dragon, and Charlie's Angels, and has been parodied in Shrek and Scary Movie. ? In June, the Wachowski brothers will release a DVD called The Animatrix, a collection of nine short films that explains the mythology behind the trilogy. ? R&B star Aaliyah, who was cast in a supporting role, died in a plane crash last August. She was replaced by Nona Gaye (Ali), Marvin Gaye's daughter.