In world tennis, a computer has last word

Behind every Martina Navratilova or John McEnroe is - a computer. No, the computer doesn't give them pointers on sharpening their backhand. Nor does it help them plan their strategy against key opponents. At least not yet.

But every week, a computer determines the rank of each of the top 1,200 players in the world. This may not seem like much. But since it was put in place 11 years ago, this system has played a key role in elevating tennis from minor- to major-league status. In 1970 there were only 20 open tournaments in the world. This year the Grand Prix circuit alone consists of 90 tournaments with more than $17 million in prize money.

''Computer ranking is really the bible of tennis,'' explains Ray Moore, president of the Association of Tennis Professionals (ATP), which administers the system. ''There are two things that a player looks at each week: the money they've won and their ranking.''

To understand the pivotal role that computer ranking plays, it is necessary to understand how tennis was run in the old days, says ATP's deputy executive director, Ron Bookman. Back then, each country had a committee that determined the relative ranking of native players on a mostly subjective basis. Tournaments were put on by promoters, who liked to match high-ranked local talent with high-ranked players from other countries. Many competitions were closed to players who were not invited.

The result, says Mr. Bookman, was a system that many players found unpredictable and discriminatory. Although the 20th-ranked player in Country A might be more skillful than the top-ranked player in Country B, the lower-ranked player found himself consistently excluded from many international tournaments, and as a result, found it hard to make a living on the tennis circuit.

The situation came to a head in 1972 when the ATP, essentially a tennis player's union, was formed. One of its first tasks was to set up an international ranking system and insist that a player's rank determine his eligibility for competing in major tournaments.

Basically, the system tracks players' performances in 275 tournaments around the world. Each tournament is graded according to the number of players entered and the amount of prize money. Winning a small tournament might net a player 20 points, while a first-place finish in a major meet like the US Open nets 270 points. In addition, players get bonus points for defeating top-ranked opponents: 30 points for polishing off one of the top five, for instance.

Each week, results from tournaments around the world are phoned or telexed into ATP's headquarters in Dallas or Paris. These are added to the points players have earned during the previous 52 weeks. The player with the most points is ranked No. 1.

Because the rankings are based on a player's performance over only the last year, champions cannot rest on their laurels, but must keep performing to maintain their standing, Mr. Moore says.

The rankings are of importance because they determine who gets into a tournament, without going through arduous qualification rounds. Thus, it has a direct impact on how much prize money a player competes for.

''The computer makes the sport go, and keeps it honest,'' Bookman summarizes.

Until recently the association did its number-crunching on computers supplied by Atari. But the company defaulted on the agreement, Bookman says. But it didn't take ATP long to find another sponsor. Hewlett Packard stepped quickly into the void and announced this week that it is supplying the group with its considerably more powerful personal computer system.

The tennis group says the change will allow it to keep more sophisticated statistics.

For example, it will start recording the results of head-to-head scores between players, how individuals perform on different surfaces, their records against right- and left-handers, serving percentages, and so on. They hope this will boost media coverage and enhance the interest of fans.