Olympic legend Mark Spitz believes security concerns may see the United States withdraw from the Athens Games.
Mark Spitz won seven gold medals at the 1972 Olympics in Munich
Spitz, who won seven swimming golds in 1972, says heightened terrorist fears may prompt drastic action from the US.
"I would say that about six months ago it was highly unlikely," Spitz told BBC Five Live.
"But each day it becomes more probable than not that ongoing conversations will take place as to how important it is to put athletes in harm's way."
A spokesman for the US Olympic Committee said: "Today there is
absolutely no consideration given to the notion our team will not be in Athens."
But Spitz believes that any US decision to pull out of the Games will come at a late stage, and could trigger a "snowball effect" as other countries follow suit.
"We are looking under the microscope at all the different terrorist acts and we know there is a high degree of probability that something could happen in Athens," he said.
"Would it be political suicide to send a team there if you were the Bush administration?
"If you were to yank the carpet out from under the American team and nothing
happened, would that be because they are only after Americans?
"If that does happen it will happen in the 11th hour and 59th minute."