The world's top swimmers will be vying to fill the void left by Michael Phelps as the world championships begin without the decorated American in Barcelona on Sunday.
Phelps, who ended his glittering career after last year's London Olympics, will be watching from the stands at the hilltop Palau Sant Jordi, a venue for the 1992 Olympics, as some of his old rivals bid to take his place as the global face of swimming.
Americans Ryan Lochte and Nathan Adrian, Australia's James Magnussen, Sun Yang of China, Frenchmen Yannick Agnel and Florent Manaudou and South Africa's Chad le Clos will be the ones to watch as the sport comes to terms with the absence of Phelps who amassed 26 world championship and 18 Olympic golds. Lochte is defending the most titles from the last world championships in Shanghai in 2011, including the 200 metres freestyle, the 200 metres backstroke and the 200 and 400 metres individual medleys.
Among the women gunning for gold medals and world records are Americans Missy Franklin and Katie Ledecky, Lithuania's Ruta Meilutyte, Chinese Ye Shiwen, Cate Campbell and Alicia Coutts of Australia and Ranomi Kromowidjojo of the Netherlands.
Judging by the form book, the Americans are likely to take the absence of Phelps firmly in their stride and top the medals table for 13th time in 15 editions since the first world championships in Belgrade in 1973.
South Africa's Le Clos caused a sensation in London when he pipped Phelps to win gold in the 200 metres butterfly and deny him a third straight title in his favourite event.
The 21-year-old suffered an injured shoulder around the turn of the year and has decided to compete only in the three butterfly events in Barcelona.
The world championships also offer a chance for traditional powerhouses Australia to redeem themselves after a woeful performance in London.