BUENOS AIRES, AUG. 8 -- The United States almost got greased -- make that Greeced -- at the World Basketball Championships today, needing overtime, a disputed call and inspired work from Billy Owens to escape its opener, 103-95.

Most of the game seemed a mismatch, but quite the opposite of the kind of mismatch most had expected. The Americans looked sluggish and disorganized, the Greeks like world-beaters.

Led by a beefy point guard named Panagiotis Giannakis and a rebound-eating center named Panagiotis Fasoulas, the experienced Greeks tossed in feathery jumpers and drove for easy layups at will, leading by 13 in the first half.

The Greeks, however, failed to put the game away when they had the chance. The U.S. team -- behind forward Owens's 33 points and nine rebounds, and guard Kenny Anderson's dazzling quickness -- slowly climbed back to tie.

A tip-in by forward Nassos Galakteros at the buzzer was ruled to have come too late, sending the game into overtime, 89-89.

At that point, the teams realized who they are. The Americans dominated, the Greeks promptly folded.

But the game revealed once again the two faces of the U.S. squad and the uncertainty of its prospects later in the tournament.

Coach Mike Krzyzewski said: "We have been inconsistent. We have been either very good or not so good, which is a sign of a very young team that has not been together as long as the teams we are playing. We can play better."

The U.S. team began wearing its unstoppable mask. Chris Smith opened with a three-pointer from the corner, then Alonzo Mourning hit a jumper from the top of the key, then Owens from the left baseline, then Anderson finishing a fast break sparked by Owens's outlet pass. After five minutes the U.S. team had an 11-point lead.

Then, abruptly, they changed identities. What had been a mobile, switching defense turned into a sculpture garden, through which guard Giannakis (23 points, 10 rebounds, 5 assists) maneuvered at will.

At one point, Giannakis tried an ill-advised baseline drive, fell down, yet still managed to find enough space around him to keep his dribble, get back on his feet, throw a couple of head fakes and sink a soft eight-footer off the backboard. Warming to the underdog, the sparse Argentine crowd went wild.

Meanwhile, 7-footer Fasoulas was acting as if he owned the middle, using his quick feet and long arms to take Mourning completely out of his game -- and to get the Georgetown center into early foul trouble. Fasoulas also used his elbows on occasion, leading Mourning to throw an errant punch that earned him a technical foul and some cool-off time on the bench.

Mourning (13 points, three rebounds) did not have one of his better games. The Greeks' strategy appeared to be to deny him position, deny him the ball and then, if all else failed, mug him. He looked frustrated most of the game.

At halftime Greece was up 11. Then, just two minutes into the second half, Mourning got his fourth foul and had to sit. At that point, when the game seemed to be slipping out of reach, Syracuse's Owens began to assert himself -- two steals, good hustle on a loose ball and a dunk.

Fasoulas got his fourth and fifth fouls in rapid succession to foul out, and without his presence in the middle, Greece began to slip. The only question was whether there was enough time for the Americans to come back. Twice they threatened to tie, only to have Giannakis make a steal, then Mourning miss two free throws. Finally, a spectacular steal and breakaway layup by Georgia Tech's Anderson tied the game at 86.

With time running out and the score 89-89, guard Constantinos Patavoucas heaved a half-court Hail Mary that just rimmed out. Galakteros tipped it in at the buzzer and Greece seemed to have won, but officials ruled that time had run out.

"I thought it was good," said Coach Efthimis Kioumourtzoglou, "but my colleagues in the dressing room informed me later that I was wrong, that time was out."

Asked how he saw the tip-in, Krzyzewski said: "It doesn't make any difference what I think. The decision gets made by the referee, and then we go on to the next decision."

Greece was runner-up in the 1989 European championships and has been improving for some time. But, with star Nick Galis (formerly of Seton Hall) unexpectedly not making the trip, no one seriously gave it a chance to beat the Americans -- no one except Krzyzewski, the Duke coach.

"Nothing surprises me in international or college basketball, especially when we're playing a very good basketball team," he said. "Yes, we can play better."

In other games, Goodwill Games gold medalist Yugoslavia beat Venezuela, 92-84; Brazil stopped Italy, 125-109; Australia rolled over China, 106-85; and the Soviet Union topped host Argentina, 97-77.