Reese Hoffa has described the prospect of a US shot put clean sweep at the Olympic Games as "very unrealistic".

Team USA have three of the top four throwers this season, with Adam Nelson leading the world rankings with 22.12 metres, Hoffa second and Christian Cantwell in fourth behind Belarus' Andrei Mikhnevich.

The shot is the first athletics final which will be decided in Beijing and Hoffa believes the American heavy brigade - if they perform at their best - can fetch Team USA's first medals of the track and field schedule.

However, Hoffa, who is aiming to banish the memory of preliminary-round elimination in Athens four years ago, believes there is only an outside chance of a one-two-three.

"I really think it's very realistic," said Hoffa. "I give it a fifty-fifty chance - I wouldn't want to go too much higher than that.

"It goes back to the pressure. Everyone goes out there and expects great things from us, they're expecting us to sweep.

"It's tough, I would love to be the class of Olympic athletes to sweep but everything has to go right.

"We have to go out there and earn it.

"I'd like to sweep and I'm sure Adam and Christian would too."

Hoffa is mindful of the Athens event, when Team USA failed to fulfil expectations.

Nelson had only one valid throw from six attempts but his effort of 21.16m was leading the field until Ukraine's Yuriy Belong matched it with his final attempt and won on countback with a second-best mark of 21.15m.

Legendary multiple world champion John Godina had crashed out and, with Cantwell, the world's leading thrower of 2004, having failed to make the US team, the form book was thrown out.

Hoffa would love to see himself, Cantwell and Nelson, who has medalled at every Olympics or world championships since 2000, on the podium together on August 15 and believes there is a possibility, but said the result would depend on the performances of his team-mates.

"It's going to come down to the kind of shape Adam and Christian are in when they get here," he added.

"Adam is a wily old veteran so he probably won't have any problems.

"I will be intrigued to see what Christian does - he could be the guy that wins the Olympics no problem, because he's so powerful."

Hoffa remains determined to help give the US squad a great start.

"I definitely think we set the tone for how the team does," he added.

"If we don't go out there and hit the marks that we're supposed to hit, then we won't dominate."