But Mandela sent a message, via South African President Jacob Zuma, that the revelers should enjoy themselves. They took it to heart.
From the start of the ceremony to the final whistle of the first match, four hours later, Soccer City was abuzz with vuvuzelas -- the plastic horns favored by South African fans that collectively sound like the amplified interior of a beehive.
Most of the crowd of 84,000 wore the yellow jerseys of Bafana Bafana, the host country's team, with a few pockets of green -- fans of Mexico, South Africa's foe in the opener.
Even the result did little did dampen the festive mood. Mexico is ranked much higher among soccer nations, after all.
And for one stretch, the home fans were in utter delirium. The level of bedlam and euphoria somehow ratcheted to a higher level when Siphiwe Tshabalala gave South Africa a 1-0 lead with a stylish goal in the 55th minute. Mexico's tying goal, 24 minutes later, subdued the noise only briefly.
It was a day that many South Africans welcomed with amazement. Only 20 years ago, their nation was still in the throes of apartheid -- and the target of an international sports boycott because of those racial segregation policies.
On Friday, whites and blacks rooted side by side for the home team. And on the clogged highway leading to the stadium, little blond children in their families' vans waved South African flags and grinned warmly at the black children cheering and dancing along the roadside.
Just before kickoff, Zuma, sporting a scarf in national colors, and FIFA President Sepp Blatter spoke briefly to the crowd from midfield.
Blatter depicted this World Cup as a triumph for Africa, which had never before hosted the event despite its passion for the game. He added: "The spirit of Mandela is in Soccer City."
The crowd then rose for the Mexican and South African national anthems -- the latter a fusion of the main hymn of the anti-apartheid movement and the anthem of the former white-minority government.
Then it was game time and the horns sounded louder than ever.
Several key players in South Africa's political transformation were there, including Archbishop Desmond Tutu, who at one point was dancing in his seat to the music. U.S. Vice President Joe Biden also was among the VIPs.
It was not an occasion for those who like it quiet, thanks to the vuvuzelas -- although they were briefly drowned out by the overflight of military jets just before the opening ceremony.
The public address announcer then begged the crowd to ease up on the noise so the global television audience could hear the music. The plea met with limited success.
An all-star cast of musicians, including South African trumpeter Hugh Masekela and American singer R. Kelly, performed. Cast members brought out large placards with the flags of the 32 nations competing in the tournament, holding them high as a final burst of fireworks ended the show.
Before long, the video screens were showing South Africa's players were dancing, singing and chanting in the tunnel on their way to the field.
Soccer City was nowhere near full at the start of the opening ceremony. Thousands of fans were stuck in traffic jams on roads leading to the stadium -- regaled along the way by groups of dancing, chanting young people in Bafana shirts and by vendors selling the multicolored South African flag.
"The traffic was mad! There should have been better organization," said 24-year-old Farzana Essop, whose party turned back before reaching the stadium, where they'd hoped -- somehow -- to obtain tickets.
Those who didn't go to the stadium had ample options.
South African city officials set up 10 official fan parks in the nine host cities to cater to fans who couldn't get match tickets.
In downtown Johannesburg, a viewing area was so packed that a crowd-control barrier was toppled at one point. It didn't stop the party.