MEXICO CITY : The World Cup kicks off Thursday with co-hosts Mexico taking on South Africa in the Estadio Azteca in Mexico City, launching a sprawling tournament of 48 teams that will last nearly six weeks.

The extravaganza hosted by the United States, Mexico and Canada is the biggest World Cup in history, stretching until the final in New Jersey on July 19.

It is projected to generate a record-breaking $13 billion in total revenue but football's world governing body FIFA has faced stinging criticism over the eye-watering costs of tickets while Donald Trump's immigration crackdown has seen a top referee, Iranian team officials and fans refused entry to the United States.

Speaking in Mexico City on Wednesday, FIFA President Gianni Infantino launched a spirited defense of the organization of the tournament and brushed off criticism over visa issues.

Infantino insisted that tickets -- which in some cases have topped $30,000 -- had been priced appropriately, citing a small number of $60 tickets that were made available in response to criticism.

"Let me just say that our entry price, which is 60 dollars, is the lowest entry price of any of the American sports in the play-off phases," Infantino said.

"Our average price which is below 500 dollars is again the lowest of the American sports on average."

- 'We don't control everything' -

Infantino also played down the controversy surrounding Somali World Cup referee Omar Artan, who was refused entry to the United States after arriving in Miami last Saturday following security concerns raised by US immigration authorities.

FIFA has since confirmed Artan, who the US State Department said had "associated with suspected members of terrorist organizations," will play no part in the tournament.

"It is unfortunate what happened to the referee from Somalia," Infantino said.

"We don't control everything... Sometimes it's good to chill, relax, we work on everything, we try to solve everything.

"Sometimes to immediately start screaming and shouting has the opposite effect of finding a solution."

The FIFA leader also portrayed Iran's participation at the World Cup in the midst of its military conflict with the US as a victory for his organization.

"People were saying Iran couldn't come to the World Cup," Infantino said. "There are challenges, it's not easy, but I don't know who else would have been able to ensure in these circumstances -- which we could not influence -- Iran could come and play."

Infantino's close relationship with US President Trump has also come under scrutiny but the FIFA chief maintained that without Trump, there would not have been a World Cup in the United States.

"Without his engagement and involvement, I think it would have been, simple as that, impossible to organize a World Cup in the United States," Infantino said of Trump.

Trump confirmed on Wednesday he plans to attend some World Cup matches, without providing details.

"I spoke to Gianni this morning... he said there's never been anything close" to the success of the coming tournament, the US leader said.

- Wall of noise -

South Africa coach Hugo Broos warned his players they will have to block out a wall of sound during the curtainraiser in the Estadio Azteca, a legendary venue that hosted the 1970 and 1986 World Cup finals.

"They will have 85,000 Mexicans shouting and singing. But we have to focus on our game. And if we can do that... then we can have a good game," the Belgian said.

Mexico have never won the opening game of a World Cup despite appearing in one seven times and coach Javier Aguirre said he was determined to put that right.

"We have to break the statistic," Aguirre said. "I'm going to share (that fact) with the players. It will be another source of motivation."

South Korea and the Czech Republic play the second game of the opening day, in Guadalajara.

Spain, France and England are the bookmakers' favourites while reigning champions Argentina will look to their 38-year-old talisman Lionel Messi to drive them to the final.