If you've ever wondered what a love affair between, say, Margaret Trudeau and Bjorn Borg might be like, "Players" could be the disillusioning answer.

As a chic layabout enamored of a young tennis player, Ali MacGraw surpasses even her own towering standards of obliviousness. What could be going through this creature's mind when she offers the camera lens that puzzled scowl for our divination?

In the French movie "No Time for Breakfast," a formidable screen actress, Annie Girardot, projects more emotional shifts and contrasts than the synthetic material can accommodate. MacGraw offers the diametrically opposite spectacle.

As certain to be laughed off the screen and written off financially as "Hurricane," another Paramount loser, "Players" should clinch MacGraw's reputation as the most ridiculous leading lady of the 70s. But the folly is not hers alone. What prompted producer Robert Evans, director Anthony Harvey and screenwriter Arnold Schulman to foist on anyone a love story as unformed and uninteresting as "Players" (definitely not to be confused with the Don De Lillo novel of the same title)?

Schulman permits himself two screen credits: "By Arnold Schulman" soon followed by "Written by Arnold Schulman, executive producer." This time next week he'll be pleading for anonymity. Is he also responsible for an ironically cruel line addressed to MacGraw's character: "All you have to look forward to next year is being one step closer to 40"?

As a matter of fact, MacGraw turned 40 on April Fool's Day. "Players" can be regarded as a Great Big Practical Joke-sort of an exploding birthday cake-played on MacGraw by foolhardy admirers.

MacGraw plays a fashionable kept woman named Nicole. She is supposed to feel torn between her patron, Marco, a remotely intimidating big shot portrayed by Maximilian Schell, and a young lover, Chris Christensen, a rising tennis star played by Dean-Paul Martin. Nicole lives in secluded splendor in Cuernavaca, cultivating her tan and sinews and dabbling in "soft sculpture." Marco never seems to leave his yacht in Monte Carlo and expects Nicole to join him for soft scrambled eggs, crisp bacon and a littel groping at the drop of a transatlantic call.

When circumstances throw Nicole and Chris together, Marco's familiar summons causes a conflict, reflected in MacGraw's portentious frown. Chris has scarely settled in as a house guest when Nicole gets a mysterious call and leaves without explanation.

They patch things up temporarily during a ludicrous poolside sex scene composed of torturous closeups of stroking hands, smooching faces and tangled hair. This vision of bliss already had been compromised by an early shot of MacGraw narcissistically stroking her upturned profile while enjoyed the breeze from a fan. It's unlikely that love this intense could ever be rivaled by any outside object of affection.

MacGraw and Martin, cast in the role because he can play tennis, do not possess the acting skill necessary to enlarge on Schulman's dim outlines and cryptic exchanges.

It's often worse these nonentities are asked to do more than stare blankly. MacGraw brings down the house in a scene where Martin has lost his temper and she pleads, "Please don't hurt me!," her hands fluttering in unintentionally funny distress. The situation improves only when composer Jerry Goldsmith obligingly drowns out the lovebirds with pretty orchestrations.

The filmmakers never come close to coordinating a romantic triangle with a backdrop of professional sports competition. The scenes of tennis training, in which Martin is coached by Pancho Gonzalez, and the scenes of tennis matches, in which he trades shots with Guillermo Vilas, the instantly charismatic Ilie Nastase and other pro stars, are nicely shot and stirringly scored, as if Goldsmith were doing jousting scenes for "Ivanhoe," but they have nothing to do with the flimsy love story.

The lack of coordination is emphasized by Schulman's flashback framing device. The movie begins with overemphatic-indeed, cliched-anticipatory shots of Martin and Vilas supposedly warming up for the men's final at Wimbledon. Martin notices a conspicuously empty seat next to Gonzalez, and the flashbacks of his affair with MacGraw are meant to be interspersed with upates on the match, a five-set ordeal. The first flashback jumps from a shot of Gonzalez into Martin's stream-of-consciousness, an obvious associative blunder.

Back at courtside Gonzalez is allowed to overreact hilariously each time Martin makes a mistake.

The structure leaves huge gaps in the continuity of both match and love story. After getting in the shellacked first two sets, Martin has somehow rallied to 6-5 in the third. While the training scenes unfold, MacGraw disappears. Not that anyone will complain. There's a more interesting relationship-even a more interesting love relationship-developed between player and coach.

When MacGraw finally turns up for the last crucial points, apparently after a brisk stroll from Monte Carlo to Wimbledon, it's no surprise to see that she's no inspiration.

Between the release of "Bobby Deerfield" a year and a half ago and "Players" now, about two dozen imbecilic romantic films have plagued the American screen. I fear the trend has yet to bottom out: "Rocky II," arriving next week, may or not prove the definitive fiasco.

Still, enough is enough. Who wants to watch the sleeping beauties in Holywood continue making laughing stocks of themselves?