A packed arena was satisfied at first.
Mexico took the lead early in the match, and when Julian Quinones made it 1-0 in the ninth minute, the home team had earlier created a high-octane chance.
Mexico, 14th in the world rankings, were huge favorites against 60th-ranked South Africa, and in terms of play there was a class difference.
However, not entirely so.
When unfortunate South African defender Sphephelo Sithole - who lost the ball before the 1-0 goal - received a red card in the 49th minute, surely the victory could still be secured?
When not much happened, the home fans began to boo the green-clad team impatiently.
However, Raul Jimenez was able to silence the boos when he headed in to make it 2-0 in the 67th minute.
Discontent turned to jubilation at the iconic Azteca Stadium in Mexico City, which became the first stadium in the world to host three World Cup opening matches.
Mexico, which is co-hosting the World Cup with the United States and Canada, previously hosted the tournament in 1970 and 1986.
South Africa suffered another red card when Themba Zwane was shown one in the 84th minute after a VAR review. But the home team was also hit when Cesar Montes was sent off in added time.
Mexico will face South Korea in the next match, while South Africa will face the Czech Republic.
