BUENOS AIRES, AUG. 7 -- Coming off a mediocre homestand, the U.S. basketball team is about to begin just what it doesn't need -- a long, grueling road trip against rivals who give every indication of simply being better.

The United States is among the four favorites in the World Basketball Championships, which open here Wednesday, and should dominate its first-round game against Greece. In fact, the Americans should have relatively little trouble with the other two teams in their bracket, South Korea and Spain, and are favored to breeze into the quarterfinals.

They also got an early break when it was announced today that the star player for Greece is not playing in the tournament. Former Seton Hall star Nick Galis, reportedly one of the highest-paid players in Europe, was not on the official roster submitted by the Greeks.

Galis, a who led Greece to the European championship in 1989, did not accompany the team to Buenos Aires, and team officials refused to comment on why he didn't.

So, while the early rounds would seem to be a breeze for the Americans, the rest of the tournament might not be so much fun.

Lurking in the wings are the powerful Brazilians, the surprising Soviets, and, most menacingly, a Yugoslavian team that looks like the class act in international competition.

The Yugoslavs beat the Americans in the final of the Goodwill Games in Seattle last week, capitalizing on a desultory U.S. performance of missed layups, bricked free throws and after-you defense. The Yugoslavs lost their best player to foul trouble and their top forward to an ankle injury, and still won convincingly, 85-79, to take the gold medal.

This time the Yugoslav team promises to be even better, with the addition of two players who missed that Goodwill Games showdown -- Vlade Divac, who plays for a fairly well-known team called the Los Angeles Lakers, and Drazen Petrovic, an associate of the Portland Trail Blazers.

Divac and Petrovic join Zarko Paspalj, who played for the San Antonio Spurs last season; Dino Radja, who was drafted by the Boston Celtics but signed with Italy's Il Messaggero Roma; and Toni Kukoc, a second-round draft choice of the Chicago Bulls.

Against that formidable array, U.S. Coach Mike Krzyzewski will go with the same lineup he did in Seattle -- Alonzo Mourning, Billy Owens, Kenny Anderson and Co. -- in yet another attempt to reestablish American international dominance in basketball.

The recent record is not good. In 1987, there was the shocking loss to Brazil at the Pan American Games. In 1988, there was the upset to the Soviet Union in the Olympics in Seoul. At the Goodwill Games there was not only the loss to Yugoslavia in the final, but also one to a Soviet team that tied the U.S. squad in knots with its pretty passes and rainbow three-pointers.

Nor does the history of this tournament, which now is held every four years, bode particularly well. The United States is defending champion, having defeated the Soviets four years ago in the final in Madrid. But that was only the second American victory, the other coming in 1954. The Soviets have won three times, the Yugoslavs and Brazilians twice each.

Once again, the United States will be pitting college all-stars against older, beefier, more experienced players. But there are also indications that the rest of the world just isn't as far behind, basketball-wise, as it used to be.

In Seattle, for example, the Soviet team that beat the U.S. squad was without three Lithuanian stars who decided not to play for political reasons. Still, they confounded the Americans, prompting Krzyzewski to say: "We didn't play that badly. The Soviets played great."

Just when it seemed safe to cash the peace dividend, a hoops gap may be opening up.

The first world championships were held here in 1950. It is a minor miracle that this year's tournament will take place at all, given Argentina's economic crisis and its understandable preoccupation with other matters, like triple-digit inflation.

As recently as last month, arrangements were ambling toward completion at an alarmingly slow pace. Then suddenly, with a typical last-minute flurry, facilities and accommodations were somehow readied -- or nearly so. Carpet was still being laid at the press center today, but credentials were available for the persistent.

The United States will play its first-round games in Group C with Greece, Spain and South Korea. Those contests will take place at the 6,500-seat German Society gym in suburban Villa Ballester, meaning the American team will have to contend daily with the horrors of crosstown traffic -- but at least will be surrounded by the cosmopolitan comforts of Buenos Aires, a sophisticated megalopolis of nearly 10 million.

The other favorites will not fare so well, comfort-wise. Yugoslavia has been sent to Santa Fe to begin its campaign in Group A along with Puerto Rico, Venezuela and Angola. Brazil plays in Group B in Rosario with Italy, Australia and China. The Soviet Union is in Cordoba to compete in Group D with Canada, Egypt and host Argentina.

The two top teams in each of the round-robin groups go on to the quarterfinals, Aug. 13-15 at the Luna Park stadium in downtown Buenos Aires. The semifinals and final will be Aug. 17-19 at Luna Park.

Among the spectators expected to take a keen interest is President Carlos Menem, who at 5 feet 5 (generously) is no threat to outdunk Spud Webb but nonetheless is up on the fundamentals. Shortly after taking office last year he scrimmaged with the Argentine squad. Somehow, most of the calls went his way.