Ed Moses says he sees no reason world 400m hurdles champion Dai Greene cannot win Olympic gold in London if he is not distracted from his preparations.
But double Olympic champion Moses added that Greene, who won world gold in September, needs to gain "more power" if he is to break 48 seconds regularly.
"People will put the medal around your neck before you even finish training," the American told BBC Radio 5 live.
"My advice is just to say 'look we'll wait and see'."
Moses, who won the second of his two Olympic 400m hurdle golds in his hometown Games in Los Angeles in 1984, was speaking to Greene in a BBC Radio 5 live special, which will air on New Year's Day.
He added: "You have got to keep your head calm. That's what I did throughout my whole career, I didn't think about winning.
"You will decide on race day what the outcome will be. Talking about the race is what blows athletes' minds.
"[Avoiding distractions] will make it a lot easier on you."
Greene, 25, ran a brilliant race to win Britain's first gold of the World Championships in Daegu, South Korea in a time of 48.26 seconds, adding the world crown to his European and Commonwealth titles.
However, the race was one of the slowest in World Championship history and Moses warned Welshman Greene, who has a personal best of 47.88 seconds, that conditions will be very different in London next summer.
"Dai ran a good race and burned everybody out, but in the Olympics it's going to be a much faster race," said the 56-year-old, who at one time during his career went unbeaten for 122 races, spanning an incredible nine years, nine months and nine days.
"The start is going to be key. Once you get the momentum coming out of the blocks, you keep that going.
"If you don't have it out of the blocks, you'll never have the opportunity to capitalise."
Moses, whose best time of 47.02 seconds means he is still the second fastest 400m hurdler of all time, added that Greene also needs to refine his hurdling technique.
"You need to clean up your hurdling in the turn," he told Greene. "You need to figure out how you can stay as close to the line as possible.
"Measure it at eight inches - if you run outside, you're running further.
"You also need to find a way to really get some power in order to be able to run 47 seconds multiple times if necessary. You might have to do that in the semi-final if you get in the wrong heat."