Hours before flying to Beijing for Friday's opening ceremony, US President George W Bush used some of his bluntest language yet in criticising China on human rights.

And more than 40 athletes competing in the Games crossed the divide from sports to politics, urging China to solve problems in Tibet peacefully and protect freedom of speech and religion.

In Beijing, excitement is building as the tortuous and troubled torch relay draws to a close and the country's 1.3 billion people prepare for an opening ceremony likely to highlight China's ancient history and modern face.

"There have been problems with the torch but now is the time for the party," said Weng Chengyu, a 28-year-old student watching the torch parade on the Great Wall.

"You see all this?," he said, gesturing at thousands of yellow-clad volunteers dancing and waving flags as far as the eye could see. "This shows how much the Chinese love the Olympics."

Patriotic music blared out from loud speakers, echoing around the wall, and drums and cymbals thundered out a pounding beat.

"We have travelled to so many cities from Olympia to the Great Wall, we have cried so many times, it is very emotional especially when you see the reaction of the Chinese crowds," said Xiaohong Lu, who accompanied the torch relay around the world.

Cheering crowds also celebrated on Wednesday night as China's women's soccer team won their opening match, beating Sweden 2-1 in Tianjin, a cloaking mist failing to dampen their enthusiasm.

Men's soccer begins on Thursday, with Ronaldinho intent on helping Brazil win a first gold medal. They play Belgium in Shenyang, while Argentina play Ivory Coast in Shanghai.

Hours before the game, though, it was still not clear if forward Lionel Messi would play for Argentina, after Barcelona won the right not to release him. The club said it would make a decision after speaking to the player, who remains in Shanghai.

Tennis starts on Sunday, with many hoping for another classic encounter between Rafael Nadal and Roger Federer in the men's singles final. But neither man seems on absolutely top form.

Nadal said he had had little rest since his five-set victory at Wimbledon on July 6, but he still hoped to give his best and win a medal for Spain. "I'm very tired but I'm okay, all things considered," he said.

Federer was in a prickly mood at a practice session on Tuesday, and then complained on Thursday that constant attention from athletes had forced him to leave the Olympic Village.

"It is impossible really, there are so many athletes asking for photos and so on. It is not ideal to prepare," he said.

EYES ON THE SKIES

Many eyes continue to turn to the skies, with smog and sweltering heat a concern for athletes. The haze descended again on Thursday, but authorities, who spent $18 billion trying to cut pollution, said air quality was fairly good.

August is thunderstorm season in Beijing, and organisers had talked of using experimental technology to 'seed' rain clouds to ensure it stayed dry for Friday's opening. In the event that may not be needed, even though some scattered rain is possible.

"During the opening ceremony it will mainly be cloudy and there will essentially be no impact upon it," the China Meteorological Administration said.

The highlight of the opening ceremony is the lighting of the Olympic flame, the culmination of a 130-day relay which became the focus of demonstrations about Chinese rule in Tibet.

Small groups of foreign protesters have also popped up in Beijing this week in a bid to grab the spotlight.

Chinese plainclothes security officials dragged away three American Christian activists on Thursday after they attempted to protest for religious freedom in Tiananmen Square.

President Bush, who says he is coming to Beijing for sports not politics, delivered a speech in Bangkok on Thursday voicing 'firm opposition' to China's detention of dissidents, human rights advocates and religious activists.

"The United States believes the people of China deserve the fundamental liberty that is the natural right of all human beings," he said, in comments likely to irritate China's leaders.

Beijing has ramped up security ahead of the Games, with missile launchers guarding the main venues and a special 100,000-strong security force on the alert for terrorists.

It can feel intrusive. Some foreign businessmen said they had been told to fill out forms with detailed personal questions, including political affiliation and source of funds.

"It just seems like everyone is terrified ahead of the Olympics that something will happen on their patch so they are overreacting," one businessman said. "If I'd known the city was going to be like this I would have left for the Games."

Nor are all Beijing's 15 million locals celebrating the Games, after thousands were forcibly evicted from their homes to make way for many of the venues and other modernising projects.

"I don't feel much joy for the Olympic Games," said one man, whose house was demolished in front of him late last year to make way for a car park just south of the main venue.