Japan scored a stunning upset of world champions Spain on Thursday in the Olympic football tournament as officials played down a flag blunder which prompted a protest from North Korea.
The greatest sporting show on earth will officially get under way on Friday, when around 80,000 VIPs and spectators will flock to the Olympic Stadium for an opening ceremony staged by Oscar-winning British movie director Danny Boyle.
However the sporting action kicked off with the opening matches of the women's football tournament at venues across Britain on Wednesday, and on Thursday it was the men's turn to take centre-stage.
While hosts Britain were due to face Senegal, it was Japan who provided the story of the day with a remarkable 1-0 win over a talented Spanish side aiming to add Olympic gold to their World Cup and Euro crowns.
Yuki Otsu was the hero for the Japanese, prodding home on 34 minutes to secure a victory which evoked memories of Japan's famous 1-0 win over Brazil in the Olympic tournament in 1996.
British Prime Minister David Cameron and International Olympic Committee President Jacques Rogge meanwhile sought to draw a line under the gaffe which prompted North Korea's protest ahead of their game with Colombia on Wednesday.
The North Koreans were furious after their players were introduced on an electronic screen alongside an image of the South Korean flag.
"This was an honest mistake, honestly made," Cameron said. "An apology's been made and I'm sure every step will be taken to make sure these things don't happen again. We shouldn't inflate this episode. It was unfortunate, it shouldn't have happened, and I think we can leave it at that."
Rogge said the incident was "most unfortunate" but was confident there would be no repeat.
Meanwhile two of the likely superstars of the Olympics -- USA swimmer Michael Phelps and Jamaican sprinter Usain Bolt -- stoked anticipation for the sporting action looming over the next fortnight with separate press briefings. It was standing room only at a press conference involving Phelps, winner of a record eight gold medals at the Beijing Games four years ago, and several of his USA team-mates.
"I'm excited. I'm here to swim as fast as I can. If I do that everything else will fall into place," said Phelps, who needs only three medals during the London Games to become the most decorated Olympian in history.
Bolt, the defending 100m and 200m champion and world record holder over both distances, was due to make his first public appearance since his arrival in Britain in a tightly controlled press conference at a London hotel.
Bolt has had a troubled build-up, losing to compatriot Yohan Blake twice in the Jamaican trials and suffering a "slight injury" which forced his withdrawal from a meeting in Monaco last week.
Four other athletes meanwhile were coming to terms with the news that their Olympic campaigns were already over after being kicked out of the games for doping offences.
Turkish weightlifters Fatih Baydar and Ibrahim Arat and Greek world indoor high jump champion Dimitris Chondrokoukis were suspended after failing drugs tests while Hungarian discus thrower Zoltan Kovago was ousted after refusing to undergo a doping control.