By Larry Fine

NEW YORK, Oct 19 (Reuters) The face of the tennis calendar will change in upcoming years, with the men's and women's tours combining for four big events and a year-ending championship, the Women's Tennis Association (WTA) chief said.

WTA Tour chairman and chief executive Larry Scott told Reuters in a telephone interview from Zurich yesterday that a new era of cooperation between the tours will spawn big changes.

''I think the sport has a unique opportunity and the time is right now to make significant improvements and changes,'' Scott said, noting he and new Association of Tennis Professionals (ATP) executive chairman Etienne De Villiers shared the progressive thinking.

''We certainly share the same vision with the ATP for the global structure for the sport,'' said Scott.

Scott said he was confident there would be four combined, mandatory events offering equal prize money for men and women by 2009 -- two in the United States in March, one in Europe before the French Open and one in the fall in Asia or Europe.

He said a combined year-ender is coming, but might take longer to launch because of schedule complications.

Scott said the four slams are the pillars of tennis, ''but in addition to the grand slams there would be four other occasions where the best men and best women come together on the greatest stages of the sport.'' The WTA chief said the main hurdle for a combined year-ender was that the women's tour was dedicated to finish its season by the end of October to provide a longer off-season for players, while the ATP's planned schedule lasted at least two weeks longer.

Scott, however, said a combined year-ender was coming.

MEGA-EVENT ''We both share the ultimate goal of bringing together a combined end-of-year championships as a true mega-event,'' Scott said. ''It would be a fitting end to the tennis story line.'' As for the four combined events in the season, Scott said the Sony Ericsson Open in Miami already fit the bill and the Indian Wells tournament could also qualify as such an event.

Scott said Madrid, Rome and Monte Carlo were candidates for the combined clay court event leading up to Roland Garros.

He said the fourth event in the autumn is targeted for Asia or Europe.

''As a sport we are obviously trying to strike a balance between supporting our established markets like the U.S. and Europe and developing markets -- Asia and particularly China are of great attraction.

''On a recent trip I made, both Beijing and Shanghai were talking about hosting. There's a lot of interest, particularly in women's tennis with all the top (Chinese) players we have.'' The women's end-of-year championships is in Madrid this year with next year's site to be announced.

''For the foreseeable future our concentration for the end of the year championships will be Europe and Asia, which is where our circuit is in the fall and where there's obviously extraordinary interest right now,'' Scott said.

REUTERS PDS HT1426