Lord Coe has admitted fans will be banned from wearing Pepsi T-shirts at the Olympic park - and could even be turned away for sporting Nike trainers.
Speaking on the BBC Radio 4 Today programme, Coe had been trying to end negativity surrounding the build-up.
Earlier Boris Johnson called on those worrying about the Olympics to "put a sock in it", stop complaining and get behind Team GB for the Games.
But Coe's admission, just a week before the games begin, will do little to create a positive feeling around the event.
Presenter Evan Davis challenged the Olympics supremo on whether he would be allowed to turn up to an event in a Pepsi T-shirt.
Lord Coe told him: "No, you probably wouldn't be walking in with a Pepsi T-shirt because Coca-Cola are our sponsors and they have put millions of pounds into this project but also millions of pounds into grassroots sport. It is important to protect those sponsors."
Asked whether he could wear Nike trainers, Lord Coe said: "I think you probably could..."
Pressed to give a definite answer, the peer told Davis: "Let's put some reality in this. You probably would be able to walk through with Nike trainers. Does that satisfy you?"
He added: "Keep going, Evan, we'll get there in the end."
Lord Coe also insisted the "Zil lanes" open only to Olympics traffic are vital for the smooth running of the Games.
He added: "The famous Zil lane, as you call it, is actually something that takes people to work. There are 140 IOC (International Olympic Committee) members, let's just put this into perspective, they will be using that lane, people going to work, many of them are presidents of international federations they will be in those venues early in the morning.
"There are, actually, using those lanes about 20,000 members of the media, of which about 700 will probably be BBC people."
He asked Davis: "Who in the organisation would you like me to step down from that... I'm really happy to take offers at this moment."
Lord Coe played down stories about American athletes being delayed by lost coaches on their journey to the Athletes' Village.
"Out of 100 journeys, one coach driver missed a turning."