Rogge promised an unprecedented anti-doping effort
The International Olympic Committee has a list of suspected drug cheats and plans to conduct more dope tests than ever before at this year's Olympics.
The IOC plans 25% more tests than at the last Games and president Jacques Rogge said they knew who to look for.
"We have a number of athletes that are on a target list," he said.
"We target them because either their blood parameters are suspect or we see a jump in performance that would hardly be explained by normal evolution."
He also said the net was being cast wider than ever before to stamp out drug cheats.
"We will not only test in competition, but also unannounced out of competition. Both in the Olympic Village, but also in all the training sites of the athletes, be it in China or abroad," he explained.
"We've also introduced a new rule, that is if an athlete is sanctioned for more than six months, he or she will not be able to participate to the next Games.
"And finally if needed, we would call support of the police to examine whether there is drug dealing, as was the case in Torino with the Austrian team."
He also said he was satisfied China had taken adequate measures to prevent air pollution being a problem during the Games, but they had contingency plans if necessary.
"We are confident atmospheric pollution will have no major impact on the Olympics," he said.
"Every event under an hour will be no problem for health, if an event is longer than one hour continuously at the same time as World Health Organisation levels are trespassed, then we might have to postpone competitions but I don't think this is something that will happen very often."
The BBC has been carrying out an on-going survey of air pollution levels in Beijing.
The WHO air quality guideline for PM10 - one of the city's main sources of pollution - is a maximum of 50 micrograms per cubic metre.
On 11 July, the reading was 115 mcg.