Basketball star Yao Ming announced his retirement Wednesday after a trail-blazing career that made him China\'s best-known athlete abroad and helped spur the game\'s global growth. The towering 2.29m (7ft 6in) star made the announcement during a press conference in his hometown of Shanghai after his last two seasons with the Houston Rockets were dogged by injuries. Yao, 30, joined the team as the first pick in the 2002 NBA draft but there was scepticism about whether the signature product of China\'s massive state sports system would ever earn the affection of the league\'s fans. But he won over Americans and became an adored national icon in China through his strong play -- when fit -- and his grace and poise in becoming the NBA\'s first Asian superstar. He exhibited that same grace during his retirement announcement, switching to English to offer a \"special thanks\" to the city of Houston. \"I would like to thank you for giving me a great nine-year career,\" he said. \"Nine years ago I came to Houston as a young, tall, skinny player and the entire city and team changed me into a grown man, not only a basketball player.\" He enjoyed a high profile, but the rigours of top-flight basketball proved too much for his massive frame and his career has been marked by lengthy absences from the court due to a succession of mostly foot and leg injuries. Nonetheless, he was China\'s first global sports super star with a personal brand valued at more than $1 billion. The eight-time NBA all-star routinely tops Forbes\' list of China\'s most valuable celebrities and his international appeal has led to endorsement deals with Nike, Pepsi, McDonald\'s and China Telecom. But the brand he has done the most to promote is the NBA. China has become the league\'s biggest market outside the US since he began playing with 300 million fans. NBA China, the league\'s China marketing company, is valued at about $2.3 billion.