At the other end of the spectrum, women will have the chance to take on the longest race - the 1500m freestyle, which used to be a male-only event - for the first time and the 800m freestyle has been introduced for men.
However, the selection policy for the British team is tough.
National performance director Bill Sweetenham insists only semi-final and final prospects will be selected for Japan and the qualifying times, which are based on the 12th-fastest time in the world last year, reflect that. Of the 34 individual events in Manchester, swimmers must equal or better the British record in 12 events just to be considered for selection.
"It's a fair selection policy," said Australian Sweetenham. "We are keen to take a team that's got a realistic chance of making finals."
British swimmers will also need to rise to the recent challenges set by rivals from Australia and America. Competing in their respective World Championship trials, four world records were broken.
Australian Ian Thorpe, still only 18, smashed Kieren Perkins's 800m freestyle record and then reclaimed his 200m freestyle world record from Dutchman Pieter van den Hoogenband with a phenomenal time of 1min 44.69secs. Hoogenband pipped Thor-pedo to the post in Sydney in front of the teenager's home crowd.
Over in Texas, Ed Moses shaved 0.07secs off the 100m breaststroke world record, clocking 1min 00.29secs, to book his ticket to Japan. And last week the 50m breaststroke record fell to fellow American Anthony Robinson with a time of 27.49secs.
Sweetenham feels that Britain, and in particular our women swimmers, can be competitive in Japan.
He said: "The women's team are strong but I am keen to see at the trials where the gaps are."
Competition for places in the women's relay teams should also bring about continued development in the 100m and 200m freestyle events.
June Croft's 19-year-old 200m freestyle record of 1min 59.74secs is one of many British records under threat in Manchester.
