Imagine the scene. Defending champion Michael Chang is struggling in a tense evening encounter in front of a packed Victoria Park Centre Court. His first serves let him down, his forehands are consistently long and Chang has no idea what has gone wrong. Suddenly, at a changeover, Chang's elder brother and coach Carl is sitting beside his sibling. In full view of the chair umpire and the crowd, he is offering some coaching advice. The umpire takes no action. When play resumes, Chang is a different player. He produces a string of aces and powerful ground strokes to get back into the match. Should top seed Pete Sampras' coach Paul Annacone join him in Hong Kong next week, do not be surprised to see him at Sampras' side as well. Hong Kong tennis fans will be the first in the world to witness sanctioned on-court coaching. The sport's ruling body, the Association of Tennis Professionals, is using the Salem Open and four other tournaments to experiment with such a scheme before it considers legalising it for the professional circuit. In a recent report, the ATP said: 'At the ATP Tour Player council meeting in Melbourne, the council supported experimentation with the rules at ATP Tour tournaments in World Series free weeks. 'As its first initiative, they agreed to experiment with on-court coaching at the following tournaments in 1998 - Hong Kong, Atlanta, Munich, Gstaad and Los Angeles. The council will then evaluate the feedback collected from this experiment at its US Open meeting.' Tickets range from $100 for the qualifying rounds to $1,200 for the final and are available through Urbtix at 2734 9009.