SWIMMING: The final step in his Olympic preparation looms, but world No.1 Cameron McEvoy is no closer to gauging how he will fare in the Rio pool.

Tipped to claim a record six Olympic gold, Australia's sprint king has left for his final international competition before Rio - this weekend's Japan Open in Tokyo.

McEvoy should be full of confidence after clocking an extraordinary 47.04 seconds at the Rio trials in Adelaide last month - the fastest 100m freestyle time outside the supersuit era.

He also became the first to claim the 50m, 100m and 200m national crowns at the same meet - but he says it gave him no indication of what to expect in the Olympic pool.

"I am proud of what I did (in Adelaide) but it won't be something that defines my preparation for Rio," McEvoy said.

"This preparation is going to be different to (national) trials.

"My training (ahead of Adelaide) had improved so much - that alone gave me enough confidence to know that if I repeated it the outcome would be good.

"Because this (Rio) preparation is so short I am not going to be able to push the boundaries too much further than I have."

McEvoy - who has the world's fastest 100m time of the year by almost a full second - can at least see the finish line to his Rio training.

He said the trip to Japan will be "just racing" and not a chance to improve on his world class times.

He has added the 400m freestyle to his Tokyo program to help him practice backing up from races ahead of Rio.

McEvoy hopes it proves invaluable experience when he contests the 100m and 200m individual events along with relays on day two and four of the Rio swimming program.

"I am about to complete the final week of the distance phase," McEvoy said.

"That's always a great thing because mentally it's nice to look back at what I have done.

"And it gets the foundation done for Rio, to carry me through seven days of racing at the Olympics."

World titles 100m silver medallist McEvoy will get a better gauge of how his times stack up ahead of Rio after the United States' trials next month in Omaha.

Australia are currently ranked No.1 in 10 individual events.

So far McEvoy has nothing to worry about.

Defending Olympic champion Nathan Adrian of the US clocked only 48.29 to claim 100m gold at the Atlanta Classic meet overnight (AEST).

AAP