Adam Peaty already hit the Nomination Standard by nearly a second but will need to replicate the feat tonight in order to be able to defend his Olympic gold.
Alys Thomas: Wrist injury forces Olympic swimmer's retirement tudno.co.uk - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from tudno.co.uk Daily Mail and Mail on Sunday newspapers.
Adam Peaty, James Guy and Alys Thomas have opted out, while Imogen Clark and Holly Hibbott join the British team in Rome after racing the Commonwealth Games.