Once, professional sports teams paid the best physicians they could find to treat their players, but that practice could soon be as old-fashioned as the house call.

These days, groups of doctors or hospitals are paying the teams.

In an upside-down scenario spawned by an increasingly competitive health-care market, hospitals and medical practices -- eager for any promotional advantage -- have begun bidding to pay pro teams as much as $1.5 million annually for the right to treat their high-salaried players. In addition to the revenue, sports franchises get the services of the provider's physicians either without charge or at severely discounted rates.

In return, the medical groups and the hospitals are granted the exclusive right to market themselves as the team's official hospital, H.M.O. or orthopedic group. In a nation of aging baby boomers and weekend warriors with aching, tattered joints and ligaments, being designated the place where sports stars are nursed back to playing shape has precious value.

''People believe if a team doctor or an official hospital is good enough for their favorite athletes, then it must be good enough for their favorite athletes, then it must be good enough for them,'' said Dr. William O. Roberts, president of the American College of Sports Medicine. ''But the purchasing power of these groups doesn't necessarily reflect their abilities.''