IT WAS a day of drama both on and off the mat at the Hong Kong Open judo championships at the Queen Elizabeth Stadium, Wan Chai yesterday. The championships, in jeopardy as officials argued over who should be the chief co-ordinator, were rescued after mediation by the Regional Council and Urban Services Departments. Following trouble at the weigh-in on Friday, the two Government departments - joint sponsors of the event - acted as peacemakers yesterday morning. And when the sporting action, delayed two hours, finally began, the competition produced one of the biggest upsets in years as two-time Olympian Alex Lee Kan, Hong Kong's 31-year-old number one men's player, lost to 17-year-old Wat Chi-kwan. On the political side, trouble had been expected after Friday's weigh-in was delayed for an hour as officials of the Hong Kong Judo Association's two warring factions insisted on appointing their own man as the tournament director. The incumbent officials had insisted that Siu Tak-wong should be the chief co-ordinator while the rebel group trying to oust them from power wanted Chan Hung-wai. After officials of the government bodies and the two judo factions got together behind closed doors yesterday, it was agreed that the association's senior sports executive Patsy Man Chiu-fong be given the post. ''We were not interfering with the association affairs but the most important thing was to get the competition under way,'' said David Leung Man-yuk, a sports promotion officer of the Regional Services Department. Incumbent vice-president Samson Mak Yiu-cheung said: ''Our executive committee had appointed Siu as the tournament's chief co-ordinator and we couldn't hand over the position to Chan just because the other side demanded it.'' When the players took centre stage, it was Judokan's up-and-coming youngster Wat who became the big talking point. He beat long-time under-60 kilograms champion Lee (Dai Kok Tsui) with a yuko - the third highest of the four scores which can be awarded for a throw. As the Open doubled as a selection trial for next month's world championships in Canada, Wat is set for a well-earned but daunting big-time international debut. Other men hoping to have clinched championship places are Kwok Ga the 86-kg category winner, Chan Gan-san (78 kgs), Cheung Siu-chin (71 kgs) and Yu Wai-cheung (65 kgs). Yu, who as a brown belt was also able to compete in the day's kyu-grade (white-to-brown belt) competition, won that event, too. The women's competition saw expected victories for top players Mo-jing-wai (61 kg), Cat Law Lai-wah (56 kg) and Chan Mei-ling (52 kg), but a fascinating 48 kgs category, wide open since Chan-mei-ling stepped up last year, saw the top three beat each other in a round-robin: Cheng Wah-fong beat Lucia Mak Li-ngar, Mak beat Grace Chan Man-sam and Chan beat Cheng - exactly what happened in a trial won by Chan six months ago. This time Cheng was the overall winner, on aggregate points, but Chan had some consolation when she beat Mak in the final of the kyu-grade event.