With 100 days to go before the World Cup, jackhammers shuddered and bulldozers rumbled Tuesday as workers wearing "Proud to be building Soccer City for 2010" buttons readied South Africa's main stadium.

Inside, the grass was smooth and inviting. But not far away stacks of pavement tiles waited to be laid, and parking lots and access roads were still to be tarred.

The site could well be a metaphor for the June 11-July 11 tournament: While most of the big pieces are in place, all the details haven't been worked out.

Over the years, World Cup organizers have been repeatedly and sometimes sharply questioned about whether South Africa, a country with high rates of poverty and crime, was capable of hosting one of the planet's biggest sporting events.

Now talk has gone from whether South Africa is equipped to host the World Cup to what kind of host it will be.

Visitors may have to make do with half-finished hotels at exorbitant rates -- not to mention college dorms or even campground tents. There are worries of traffic jams, as fans who can't get hotel rooms in host cities head out after games to accommodation farther afield. South Africa's public transit system is erratic at best.

And will those fans be safe?

Despite the uncertainties, the mood was celebratory and determined Tuesday at 100-days ceremonies across the country. South Africans performed a dance based on soccer moves and sang the national anthem, stressing that hosting the tournament requires enthusiasm and national unity.

"As South Africans we have encountered a lot of skepticism but today, as we celebrate this milestone, we can confidently say to the world that we will be ready," Danny Jordaan, head of the South African organizing committee, said in Durban, where the South African national team was to play Namibia at the new stadium there Wednesday.

Sepp Blatter, president of FIFA, said soccer's global governing body has never questioned South Africa's ability to organize the tournament.

"Everything is on track and ready," said Blatter, who joined Jordaan in Durban, one of nine host cities. "The African continent will host the World Cup. So why don't certain groups in the world want to believe it? It is so easy to just trust and have confidence."

Half of the 10 stadiums where World Cup matches will be played are new, and Soccer City in Johannesburg underwent an overhaul so thorough it might as well be new. Other preparations included major roadwork across the country. Seven airports were renovated and an eighth was built.

Journalists on a tour of Soccer City last week found stadium seats in place, their orange plastic contrasting with the glistening grass. Goals were up and sprinklers were running.

Outside, however, workers were still laying pipe deep under what will eventually be roads. Stacks of bricks lay scattered about and wires dangled from unfinished light fixtures.

The United States will make its sixth consecutive World Cup appearance in South Africa, and Americans have been the most aggressive foreigners when it comes to ticket sales, purchasing more than 84,000 as of November, according to FIFA. Another sign of U.S. interest: ESPN and ABC will have crews on site for all 64 games, a change from 2006 in Germany. ESPN2 will go all-soccer for a 24-hour countdown before the opener and ABC expects a huge rating for the U.S.-England game on June 12.

Still, the worldwide economic downturn -- along with those nagging concerns about security, adequate transportation and hotels -- is diminishing expectations for a tourism bonanza. FIFA general secretary Jerome Valcke said last month that South Africa wouldn't get 450,000 visitors as it had predicted and turnout could be as low as 350,000.

"People don't like to come halfway across the world for what they perceive to be an adventure," Jaime Byrom, executive chairman of the FIFA partner in charge of organizing accommodation during World Cups, told reporters recently.

The government has ordered investigations into price-gouging accusations.

In an interview with The Associated Press, Jordaan said transportation was among the "things we have to fine tune."

Under apartheid, little was done to meet the transportation needs of the black majority, and the government has struggled to catch up since democracy was ushered in, back in 1994.

The World Cup lent urgency to plans for government-run rapid bus transit systems to supplement the erratic, often dangerous private minibus services on which commuters in South Africa's cities rely. But construction delays have slowed the new service, which was violently resisted by private operators and met objections from residents of wealthy, mostly white neighborhoods through which proposed bus routes have been drawn.

The Gautrain, a new light-rail service linking Johannesburg, Pretoria and Johannesburg's international airport, will not be fully operational in time for the World Cup.

Chris Hlekane, general manager of Johannesburg's airport, said Tuesday he was worried about passengers crowding airports because they had no way to get to their hotels. He said city officials have been approached about temporarily doubling to about 200 the number of taxi drivers licensed to operate at Johannesburg airport.

The University of Cape Town has stepped in with some solutions. Schools will be closed during the tournament, and the university plans to rent out its dorm rooms and put buses usually used to shuttle students to World Cup use.

"It will be congested, slow and difficult," said Gillian Saunders, a strategist who has tracked South Africa's preparations. "But we will get through it."

Saunders said South Africa has seen a 25 percent increase in hotel rooms over the last three years, but some World Cup visitors will still end up in tents and dorms because building enough permanent hotel rooms for one mega-event would not have made good business sense.

Safety is a particular concern in a country known for high rates of violent crime.

South African police have recruited 55,000 new officers and bought $88 million worth of equipment, including six helicopters, 10 mobile command vehicles, body armor and water cannons for the World Cup.

National Commissioner Bheki Cele noted foreigners have been safe at a string of international events in South Africa, ranging from the 1995 Rugby World Cup to a U.N. summit on poverty in 2002.

"This will be the biggest one of all," Cele said.