JOH'BURG: South Africa erupted in a cacophony of hooting at lunchtime Wednesday as people across the country answered a call to "get behind" the national football team, two days before the World Cup by blowing vuvuzelas or their car horns.

In Johannesburg, the buzzing sound of vuvuzelas rang out across the city at noon and on public SAfm radio, the usual 12 o'clock news was delayed while someone blew one of the noisy plastic trumpets on the national airwaves.

In the city's Sandton business district, thousands of people clad in yellow national football jerseys gathered to greet the South African team on an open-top bus tour of the district.

As part of the United We Shall Stand campaign, which was conceived by a hotel group and two private Johannesburg radio stations, the supporters will join hands and form a human chain around the team.

South Africa is gripped by football fever in the run-up to the first World Cup in Africa.

The home side, which is nicknamed Bafana Bafana, takes on Mexico in the opening game at Johannesburg's Soccer City stadium Friday.