In the 16 years since the concept of a year-end tennis tournament bringing together the top players in the world was born, a proper format has been an elusive goal.

The Masters tennis tournament has been played as a round robin determined strictly on points, as a round robin leading to the semifinals, as a single-elimination 12-man tournament and this year as a single-elimination 16-man tournament.

No one ever has been completely satisfied with any of the formulas. The eight-man round robin that was used until 1983 was abandoned after Jimmy Connors accused Ivan Lendl of tanking a match in 1981 to avoid playing Bjorn Borg in the semifinals.

Now, the Men's International Professional Tennis Council, which took over the tournament this year and renamed it the Nabisco Masters, is thinking about giving the round robin another try. This year, for the first time, the Masters will be played at the end of the year and truly will be the last tournament of the year, rather than stuck into the schedule in mid-January.

Next week, the council will vote on a proposal to cut the field back to eight players largely because attendance for the first round of this year's 16-man tournament was so poor -- less than 10,000 both nights. If the eight-man concept is adopted, the early rounds again will be round robin -- with a catch. Instead of simply using the round robin as a means for determining semifinalists, the round robin itself will have a cash value.

If a player goes through undefeated, he will earn a bonus, perhaps as high as $50,000. The council hopes it will mean that a player with a 2-0 record who already has clinched a semifinal spot will have a reason to play hard.

There is a slight possibility that when the contract with Madison Square Garden ends in 1988, the Masters will be moved, perhaps to Paris.

The tournament moved around the world until settling here in 1978 and there is some feeling among the European members of the council that it should move again. But given the success the tournament has had here and the fact that New York is as close to a centrally located city as there is in the tennis world, a change isn't likely.

The only thing that might change that is a decline in attendance brought on by the slide of American players. This weekend's matches will draw at least 15,000 each day but most people expected John McEnroe and Jimmy Connors to be playing. It will be interesting to see how tickets sell in December if it appears that the tournament will be foreign-dominated.

The decision to change the dates of the tournament already has had one negative effect. Because Dec. 1-7 falls during football season, NBC is dropping coverage of the final weekend. ESPN, which carried the first four days this week on cable, will now televise the whole tournament.

ESPN has just signed a contract to do the weekday matches from the French Open.

The change in the dates for the Masters means that the Australian Open will move from December to January, beginning in January 1987. One year later, the old grass courts at Kooyong Stadium in Melbourne will be abandoned for a new $60 million tennis complex in downtown Melbourne. The current plans include a retractable roof for the center court.

After toying with the idea of using an artificial grass surface, the Australian Federation is now likely to use a hard court surface like the one used at the National Tennis Center in Flushing Meadow. The reason for this is that to justify the huge expense for the complex, the courts must be all-weather and available to the public year round.

In running the Masters for the first time the council, rather than using local umpires and linespeople, has brought in top officials from around the world. To emphasize this point, the council has put a little flag from the country of the umpire on the back of the chair. A little overkill apparently never hurts.

Last summer, at the height of Boris Becker-mania, Lendl said, "I am sick of hearing about Boris Becker." This week, Mats Wilander showed up at a press conference after losing a match to Becker wearing a new T-shirt.

It said: "We love Boris."