Caeleb Dressel's stunning success at the FINA World Championships culminated in the American swimmer matching Michael Phelps' record haul of seven gold medals on the final day of action in Budapest.
Already the star of the meeting after becoming the first man to win three golds in a single session on Saturday, Dressel picked up yet another title 24 hours later as part of his country's men's 4x100-metre medley relay team.
The 20-year-old swam the butterfly leg for the United States, with Matt Grevers (backstroke), Kevin Cordes (breaststroke) and Nathan Adrian (freestyle) the other contributors to a successful title defence.
A time of three minutes and 27.91 seconds saw the USA beat Great Britain by just over a second, with Russia taking bronze.
Lilly King was the standout performer on Sunday, winning the 50m breaststroke title ahead of Russian rival Yulia Efimova and Katie Meili in a world record time of 29.40secs.
King also swam the breaststroke leg as the USA's victorious women's 4x100m medley team set another world record, while Chase Kalisz took gold in the men's 400m individual medley.
Sweden's Sarah Sjostrom followed up her 50m and 100m butterfly successes by earning a third gold in the women's 50m freestyle, her time of 23.69s marginally slower than the world record of 23.67s she managed in the semi-finals.
Camille Lacourt won France a belated first gold in the men's 50m backstroke, home favourite Katinka Hosszu continued her dominance of the women's 400m individual medley and Gregorio Paltrinieri retained his title in the men's 1500m freestyle.