Germany's Paul Biedermann received a boost ahead of his head-to-head with Michael Phelps by breaking the world record in the men's shortcourse 400m freestyle at the World Cup swimming meet in Berlin on Saturday.
The 23-year-old German clocked 3 mins 32.77secs to break Australian Grant Hackett's previous mark of 3 mins 34.58seconds, despite only getting the green light to race on Friday after recovering from a thigh injury.
Biedermann inflicted the first defeat on Olympic champion Phelps in four years at the World Aquatics Championships in Rome last summer in the 200m freestyle and also took the American's world record.
The pair are set to clash again in Berlin on Sunday when the men's 200m freestyle heats get underway in the mornings with the finals on Sunday evening.
"I am really pleased with the race, the leg was a bit sore before and I needed 45 minutes to get into my suit," said the German.
"I am looking forward to racing Michael."