A swimmer has admitted to cheating and a cyclist said he deliberately crashed, but they'll get to keep their Olympic gold medals.
South African Cameron van der Burgh has admitted using an illegal 'dolphin kick' on his way to beating Australian Christian Sprenger in the 100m breaststroke final.
But with no under water technology, swimming's ruling body FINA is unable to sanction him.
And Britain will keep its men's team sprint gold despite one of its cyclists admitting he deliberately crashed to give his team a better start.
The International Olympic Committee (IOC) and the International Cycling Union (UCI) both say they have no reason to investigate the incident in which Phillip Hindes crashed shortly after taking off to force a re-start in the qualifying round on Thursday night.
"I have spoken to the UCI and they obviously aware of the situation," IOC communications director Mark Adams said on Friday.
"At this stage they don't see any reason to question the result and neither do we."
Hindes admitted the team's plan was to deliberately crash if the trio had a poor start.
Under cycling's rules, riders can request a re-start if they experience mechanical issues during the first half lap.
Hindes, 19, and teammates Chris Hoy and Jason Kenny then went on to break the world record as they beat France in the final.
"I just crashed, I did it on purpose to get a restart, just to have the fastest ride. I did it. So it was all planned, really," he told reporters trackside after the final.
Within half an hour, he had changed his story at the formal press conference.
"No. I just went out the gate and just lost control, just fell down," he said.
While French coach Florian Rousseau accepted the outcome and admitted the British were much stronger, he said the UCI must re-examine its regulations to prevent future controversy blighting the sport.
"I do think the rules need to be more precise so we don't find ourselves in an identical situation at another Olympic Games," Rousseau said.
"The fact that he did it on purpose is not very good for the image of cycling."
Van der Burgh said he couldn't afford not to use the dolphin kick because almost everyone does it.
Underwater footage shows him performing three 'dolphin kicks' at the start of the race, even though FINA rules only allow one kick.
"It's not obviously, shall we say, the moral thing to do but I'm not willing to sacrifice my personal performance and four years of hard work for someone that is willing to do it and get away with it and has proven to get a way with it like they did last year," van der Burgh said.
The incidents come days after four badminton pairs from South Korea, China and Indonesia were disqualified for deliberately losing their matches to gain an easier quarter-final draw.
Britain won its sixth gold medal of the Games on Friday when Katherine Grainger and Anna Watkins won the women's double sculls at Eton Dorney, but New Zealand has emerged as the dominant rowing nation.
Mahe Drysdale won gold in the men's single sculls 40 minutes after men's pair Hamish Bond and Eric Murray won their final, giving New Zealand three rowing golds.
Athletics competition started on Friday, with Qatar's first female track athlete Noor al-Malki, given a wild card by the IOC, stumbling out of the blocks and falling to the ground within a few steps of her heat.
Saudia Arabia's first female Olympian didn't last long in her opening judo bout either.
Wojdan Ali Seraj Abdulrahim Shahrkhani, wearing a modified headscarf, was out of her bout with Puerto Rico's Melissa Mojica in just 82 seconds.