"I think it's going to be phenomenal " says Canada's High Performance Director John Atkinson.
" The challenge of any Olympics is who can be recovered to swim multiple times in nine days. How you maintain your performance, how you recover, how you take care of yourself, are going to be the key elements because it 's not always the fastest swimmer who wins "said the British coach.
The American hopesin the men's races rely on Caeleb Dressel in the 50 and 100 meter freestyle and 100 butterfly, but the medals are likely to be scattered.
The Russian Anton Chupkov is the favorite in the 200m breaststroke and Hungarian Kristof Milak the man to beat in the 200m butterfly.
Remarkably, The States team United have won gold in the men's 100 and 200 backstroke in the last six Olympics, but that streak is really under threat in Tokyo, with American Ryan Murphy struggling to repeat his 2016 successes.
Russians Evgeny Rylov and Kliment Kolesnikov are serious contenders in a very deep field in the 100m backstroke while in the 200 world champion Rylov is again well placed and Briton Luke Greenbank is also in the frame.
Greenbank compatriot Adam Peaty is the big favorite in the 100m brasse, having recorded the best 16 times of the event, while another Briton, Duncan Scott, has a strong chance in the 200 m freestyle.
There may be no fans in the arena, but there could be home glory in the 400m individual medley with Japan 's Daiya Seto faces American Chase Kalisz.
In the women's races, American Lilly King confidently asserts that the United States could win any individual medal would require a series of surprises.
The United States is ranked number one in only five of 14 races with Australia in first place out of seven.
Five-time gold medalist Katie Ledecky, who hopes to become the Olympic swimmer most successful of all time, faces a real challenge from the Australienne Ariarne Titmus in the 200m and 400m freestyle where she triumphed in Rio.
Australians are confident in memorable team games powerful with Cate Campbell chasing gold in the 50 and 100 free and Kaylee McKeown the favorite in the 100 and 200 backstroke.
But the Australians know that while the rankings suggest it could be a golden week in the pool, their rivals have a habit of delivering when it counts.
" Americans have proven historically at the Olympics that they perform well. So for us you know they are the standard that we are looking for. And they have deserved it, "said Australia head coach Rohan Taylor on Thursday.
"On paper it looks like we look ( alright), but you know ow when you come to this competition, it's aboutwho has the competitive IQ to perform under pressure, the American system breeds competitive athletes, their entire college system, the best competitors come out of the top.
"But we think this year I think we have very competitive athletes and very competitive mentally " he added.
King will repeat the 100m breaststroke battle with Russian Yulia Efimova, a duel that erupted in Rio when King waved a finger at the previously suspended Russian and called her a drug cheater. loading
While King 's prediction of a sweep seems highly unlikely, it would not be surprising to see her again on the top step of the podium . Report by Simon Evans, edited by Ed Osmond
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