Forget Cesar Cielo (well, not quite...). James The Missile Magnussen is under fire from Aussie teammate James The Rocket Roberts, a man on 47.63 this year over 100m freestyle, that time matching what it took Magnussen to lift the world crown in Shanghai last year.

Magnussen has since moved on. And how: 47.10 ahead of Roberts at Australian trials. Roberts believes what all competitors must: the best is beatable. 

"I always say anyone is beatable," Roberts, 21, told reporters at the Australian team holding camp in Manchester. "Anything can happen on any given day and nothing is a certainty in sport. I'm confident of the work I've put in over the past few months and I'm just real excited to get in and race."

Roberts recalled Libby Lenton heading intone Athens 2004 as a threat to gold in the 100m free - and Jodie Henry coming home with the big prize. It can happen. It has happened, Olympic history a high tide of upset come the biggest of moments.  

There is no assumption from Roberts that he can will by some fluke: he believes he will need to step up if he wants the prize that Magnussen also has in mind.

"I've been improving at a pretty rapid rate so it's going to be tough to make those big jumps again,'' said Roberts, coached by John Fowlie at the Australian Institute of Sport.