He is certainly the world's highest-paid poet, more than $700,000 last year, but the intriguing question is whether Argentine Guillermo Vilas, 25, is now or will ever be the best at his prime source of income—tennis. Can a scribbler of verse diverted with existential doubts hold the court with Sweden's Bjorn Borg, who works on his English reading comic books? Will a sensitive sort like Guillermo be able to cope with the nubile muses chasing him on tour as readily, say, as Jimmy Connors?

"The guy is a bull," marveled Connors after a recent loss to Vilas. "He does everything better." But the sports pages tend to correlate preeminence in the game with "killer instinct," and despite his U.S. Open championship and No. 1 ranking in '77 in earnings, Vilas may lack that. (He is also out of contention at the moment, home in Argentina for four weeks to heal an injured ankle.) "A killer instinct," philosophizes Guillermo, "is a guy who doesn't think. Borg and Connors have it," he says. "They don't care what they have to do to win." But the humane and humorous Vilas, who has been known to argue with a linesman if he thought an opponent got a rotten call, is not putting down the other members of tennis' reigning trinity. "A killer instinct helps," he remarks, "but it is not the answer." Scoffs Guillermo's coach, Ion Tiriac: "What is this but an American term? If Connors and Vilas had machine guns instead of rackets, neither would shoot."

Maybe the answer is not a killer instinct but a tennis mother, and if Gloria Connors has been perhaps Jimmy's main goad, then Guillermo's future rests with his new mentor. "Once I decided to have Tiriac as my coach, I believe in him 100 percent," says Vilas. "I make him work like a mad dog," growls Tiriac, 38, the onetime Rumanian singles champion known as "Count Dracula" to the press. During tournaments the bearlike Tiriac sits courtside answering Vilas' imploring "What next?" glances with all the sign-language subtlety of a third-base coach. "I let him control," explains Vilas, "because he knows more than I. He tells me what to do on the court."

Although Vilas had known Tiriac for years ("He was always needling me with questions," recalls Ion), it wasn't until Vilas' upset loss to Manuel Orantes at Forest Hills in 1975 that Guillermo sought Tiriac's help. In January of 1977 Ion signed on full-time for an undisclosed piece of Vilas' action. "We try not to talk publicly about money between players and coaches. Otherwise, we get into 'Who cheats whom?' " says Guillermo. "Already it is difficult to be friends."

Acting as accountant, secretary and chaperon—as well as coach—Tiriac has been accused by some of even telling Vilas which women he can date. "Like hell, I wish I could," Tiriac protests. "I prefer having him in the hotel room writing his poetry. You know, we cannot understand each other. I am fists-on-the-ground type, and he—he is head-in-the-sky." Once a notorious womanizer himself ("Now I am too old for that job"), Tiriac ironically has sometimes found himself shielding Vilas from groupies or potential jet-set distracters like Bianca Jagger.

"When I was going with one lady and I lost, everyone said it was her fault," Vilas reflects. "Then I started with another and I won. That time everybody said, 'This one, she is good for you.' People say that Connors lost because of Marji Wallace. All this kind of talk is stupid," figures Vilas. Still, he does find that a woman in his life can reduce his on-court concentration. Thus, before a big match he tends to spend the evening alone. "I am more of a worker. I have to rest a lot when I am training and in tournaments. I prefer to be alone than in bad company," he adds. "In fact, I like to be alone—to be able to sit on the John with the door open."

That may be his last sanctuary from taskmaster Tiriac. A few weeks ago at the Colgate Grand Prix Masters in Madison Square Garden (where Vilas beat Connors but lost to Borg), Guillermo, for example, followed Tiriac into the dining room of New York's Plaza Hotel. Tiriac quickly selected a table. Taking command, he ordered a Heineken for himself, then checked to see that Vilas had water.

"What is this?" Tiriac asked the waiter, pointing to the Breast of Capon Eugenie on the menu. "Chicken," replied the waiter. "With what?" Tiriac demanded. "A velvety cream." "No good. Bring the filet mignon with vegetables," ordered Tiriac. Vilas nodded his Stevie Nicks locks dutifully. Eyeing his steak, Vilas reached for the salt. "It retains water," cautioned Tiriac. After eating, Tiriac ordered a syrupy espresso for himself. "Tea?" asked Vilas softly. "Please bring an extra pot of hot water," Tiriac told the waiter. "You must dilute it," he said to Vilas.

On the road Vilas spends his evenings in his hotel room working on his second book of poems. His first, Cientoveinticinco (One Hundred Twenty-Five) came out in Buenos Aires in 1975. He published the initial 7,500 copies himself and priced it at $1.50 per copy. Since then, however, 15,000 copies have been sold. When Jorge Luis Borges, the blind Argentinian gentleman of letters, was asked what he thought of Vilas' poetry, he responded: "Just imagine me playing tennis." Vilas says modestly, "I can't say it is good—just that it is a personal statement."

"The meaning of the number in the title," he says, "is a secret. There must be one thing in my life which only I know." It is a collection of 41 spare, sometimes haiku-like poems about love, fear, death and identity. "I cannot write when I'm content. When something nice happens, I live it. When something sad happens, I write it."

Along with the new volume of poems, he is also working on the 10th draft of a screenplay, The Deciding Years. The principal character is a man in his early 20s, a composite of Vilas and two university friends. "It is heavy," explains the devoted fan of Bergman and Buñuel films. "There are a lot of personal experiences in it. Suicide is one of them. But for me it is happy."

Vilas was born in the resort city of Mar del Plata 220 miles from Buenos Aires. His father is a lawyer (who also dabbles in poetry). Though they own four houses, "We don't have many servants because the women, unlike in America, stay home and take care of the house," explains Vilas. "In Argentina you don't push buttons for your wash. My mother must start cooking at 10 to have a meal ready by 1." That is still the same even though "Willy" (as he is known in his native land) has become a national hero.

His father, whom Vilas resembles ("We are both Leos and have big noses"), encouraged him to play tennis because little Willy was playing soccer on the highway. ("If Willy had stayed with soccer, he would be No. 1 today," his father boasts.) An obedient child, Willy began tennis at a nearby club where Dad was president. "I was very bad at first so I quickly played a lot to get over my embarrassment," he recalls. By 17 he was the leading player on Argentina's Davis Cup team. In 1969 he chose tennis over law as his vocation.

At home in Argentina, Vilas has many male friends, but few female. "Men and women are different in terms of friendship. A woman marries a man who is jealous and then she can't be my friend," he says. "Sex, in my country, isolates men and women."

Despite the customs there, Vilas has managed quite a string of romances. His first public liaison was in 1975 with a six-years-older Argentinean beauty queen and model, Mirta Massa. While traveling together in Venezuela, she mentioned their "engagement." Vilas called her "a very good friend. I was crazy for her. I mean, split in two for her. But this love ended because of the way she is. One day she began to bother me. I think we're still friends." That must be so. No ex-love has gotten a greater review than Guillermo. After their separation, Mirta said of the relationship: "He looks like a kid, but he's mature. He's intelligent, simple, sensitive, open, warm." The worst she will say was that he was "difficult to live with on the eve of a match." Then the praise continues: "He loves everything which has anything to do with art. He doesn't have much interest in cars or clothes. He is not an egotist."

After Mirta came Elianne Haddad, 22, the daughter of a Brazilian industrialist. She plays tennis well and, like Vilas, is a rock music fanatic. "Willy is sensational. Our relationship doesn't need marriage," she said. "No relationship between a man and a woman can have a fixed date. Our thing is not a contract. It is something free." Free it was; it vanished after a few months. Ever since, Vilas has been with Gabriela Blondeau, 16. They first appeared in public at an Andean resort with her brother and Tiriac trying to play chaperons. Gabriela does not, however, travel outside Argentina with him.

Vilas is ambivalent about marriage. "If I had to—some families in my country might insist—I would sign with my eyes closed. I think marriage kills something. It is one thing to quarrel with your girlfriend, another with your wife," he says, and then adds thoughtfully, "Maybe, though, I would marry for children. Some time ago I thought about adopting a child, but then I realized that it is much better to have one with the person I love."

Vilas does not consider himself a classically male chauvinist Latin. "When I need help, I hope to get it from the woman beside me. When she needs help, I give to her," he says. Yet, if he does marry, he doesn't want his wife to work. "In Argentina many women don't work and they are happy. After 30 I don't plan on working," he figures. "I want to travel and expect my wife to be with me," he says.

A resident of Monte Carlo for tax purposes, Vilas' spiritual base is a plant-filled, riverview, four-bedroom apartment in Buenos Aires. His car is a Fiat 128, "prepared for speed."

"When I am not playing tennis my life is different," he says. "All afternoon I am on the beach. Fresh fish is served for dinner. I dance till 3 a.m., go to bed at 6 and sleep until the next afternoon. It is wonderful." Besides doing Colgate hair conditioner commercials on Mexican television ("I'm not the best, but I'm not the worst"), he also endorses Fila, an international sportswear line.

Although he quotes Kahlil Gibran in his book of poems, Vilas doesn't meditate or go in for est or such cults. He is a practicing Catholic, who recently sent a list of theological queries to his bishop. Perhaps the thing he understands best is fear, especially of flying, which can't be avoided in his line of "work. (Upon takeoff he pulls on his headset and plugs into his ever-present personal tapes of Utopia, Chick Corea, Weather Report, Herbie Hancock and Fleetwood Mac.)

As he wrote in one of his poems:
Fear,
Cursed fear,
To be so cold a thing,
Inert and expressionless.

"There is so much more to life than hitting a tennis ball," Vilas says with a small smile. "But right now I am doing the right thing at the right time."