Gloomy thoughts of wet concrete and slow ticket sales were swept away by a summer wind on Monday as the "last-minute" magic long promised by Greece lined up the Olympic Games for a smooth takeoff in four days.

Fears that some arenas would be half-empty because of foreign security concerns and Greek congestion worries had been banished by a surge of ticket sales, organisers said.

"We will have a full house in Athens," Olympic Committee (ATHOC) spokesman Michael Zaharatos predicted.

Organisers aim to sell at least 3.4 million tickets by the start of the Games on Friday and say demand is accelerating towards the ultimate goal of 5.2 million seats filled.

"We have said all along it would be a last-minute thing with us," a Games official told Reuters.

Return visitors said Athens seemed transformed by the expressways and metro train lines built for the Games.

FIRST DOPING FINDS

As 16,000 athletes, coaches and officials from 202 countries settled in at Olympic Village, doping tests turned up the first unwelcome results of the 49th Olympiad before it had begun.

Irish 10,000 metres runner Cathal Lombard admitted taking a banned performance-enhancing drug and two Greek baseball players tested positive for banned substances.

Lombard, 28, who failed a test for the endurance-enhancer erythropoietin, or EPO, was quoted in the Irish Examiner daily as saying "hands up, I did it".

"Subject to looking at all the information, I would be unlikely to contest the findings," Lombard told the paper.

Lombard would fly home on Monday, media reports said.

A Greek baseball team spokesman refused to give the names of the two players who failed their first drug test until a second had been carried out. But he said it was "100 percent that two Greek-Americans have failed".

The newspaper Eleftherotypia quoted the Greek baseball federation's Panagiotis Mitsiopoulosone as saying one had tested positive for a steroid and another for a diuretic "in the first sample taken by the Greek Olympic Committee".

One had advised in advance that he was taking a prescription diuretic medicine for a medical condition. The second case involve the banned steroid stanozolol, the drug that wrecked the career of Canadian 100 metres runner Ben Johnson after winning in the 1988 Seoul Games.

SMILING SECURITY

More than half of the two biggest contingents, from the United States and Australia, had checked in at the athletes village where air-conditioned coaches that smelled new off the assembly line were delivering more in a steady convoy.

"Everybody is just relaxing. We're not really nervous, but I guess that will start soon," said Dutch swimmer Annabel Koster.

The risk of a terrorist threat at the first summer Olympics since the September 11, 2001, attacks on the United States has raised security precautions to unprecedented levels, but so far not unbearable. Smiles are as abundant as the sunshine.

"There's no sense in being worried about it all the time," Koster said. Adam Pecina of the U.S. medical team agreed: "It is increased, but you don't really notice it."

The widow of a British diplomat who was the last man to die in a terrorist attack in the Greek capital, in June 2000, said the Olympics were a fitting memorial to her husband.

"If he had not been the last to die, we might not be watching the Olympics in Athens," Heather Saunders told Reuters.

"I hope that any organisation wanting to destroy the bonds of the Olympics would leave well alone. It is one of the few things left in this world that brings people together from all over the world."