Thwack . . . thwack.

Thwack . . . Thwack.

Thwackthwack.

Thwack . . . Thwack.

THWACK! . . . thub-thub-thub-thub-thub.

This is the soundtrack of "Players," a tennis movie.

It's also the structure of the main plot, a Wimbledon match between Dean-Paul Martin and Guillermo Vilas, and of the subpolt, a losers-take-all match between Dean-Paul Martin and Ali Macgraw.

MacGraw plays a 39-year-old woman - if that's the meaning of the figure "close to 40" that is pronounced to her several times like a sentence - who is kept in Cuernavaca, Mexico, for occasional use in a yacht anchored off Nice, France, by a middle-aged man with more money than geography, played by Maximilian Schell. she has come to this life, she explains, by ways of Vassar and several United States senators, which absolves Wellesley, MacGraw's school, of responsibility for her bad Spanish and worse French.

Martin plays a 23-year-old tennis-playing hustler who picks her up out of an exploding car and accepts a lot of her hospitality.

She serves him ("I want you for a month") and he returns it smartly ("All you had to do was ask nicely") and she thwacks the ball at him ("I think you wanted to hurt me") and he lets it thub-thub-thub-thub ("Everytime you speak French, it means you're going away").

Will they go straight and make the bigtime? He enlists Pancho Gonzalez to coach him for honest tennis, and she struggles between choosing honest young love and rotten old moneyed love.

All this takes place between points of a Wimbledon game that he is trying to play while keeping one eye on her empty seat. The seat is labeled 30, which is either symbolic of the decade she is completing or represents newspaper jargon for The End.

Probably both.