American swimmers smashed records and grabbed gold at the world championships on Friday, with sprint king Caeleb Dressel taking down Michael Phelps' 100 metres butterfly world record and teenager Regan Smith lowering the women's 200 backstroke mark.
The 18-year-old, who broke the world record in Saturday's 50m event, smashed his own world junior mark while winning the 100m final in a Russian senior record of 52.53 seconds.
Dmitry Balandin of Kazakhstan snatched a shock victory in the men's 200 meters breaststroke on Wednesday as the Central Asian country grabbed two Olympic gold medals in the space of an hour.