Lilly King collected her third and fourth gold medals of the 2019 World Championships, the swimmer also helping the United States set a relay world record.

King had suffered disqualification in the 200metres breaststroke but somewhat made amends by defending her 50m world title on the final day of competition on Sunday.

The American held off a strong challenge from Benedetta Pilato - the 14-year-old Italian prodigy taking silver - to become only the second woman to win the event at successive world championships.

"I was planning to be racing every day this week so it kinda changed up training plans and things like that," King said of her 200m DQ. "But other than that I was just trying to move on and refocus my energy on the 50."

King then played a key role as Team USA claimed glory in the 4x100m medley relay, 200m champion Regan Smith getting them off to a flyer with her world-record split allowing Simone Manuel to ease home and knock a second off the race's world record.

Manuel also added 50m free gold to the 100m title she claimed earlier, beating defending champion Sarah Sjostrom into second with the bronze medal going to Cate Campbell.

Sjostrom was named the best female swimmer of the meet regardless with the male award going to Caeleb Dressel, whose USA team were beaten in the men's 4x100m medley relay.

Gold in that event went to Great Britain, for whom Duncan Scott and Adam Peaty starred with their rapid legs helping to set a new European record.

Daiya Seto became the 400m individual medley world champion with the Japanese now out to impress at next year's Olympic Games in Tokyo.

"I was very scared [of being caught]," said Seto, who also took 200m individual medley gold at the meet. "But I want to win - I want to be Olympic champion next year. The 400 is my main event. I enjoy it, but [it's] very hard."

Katinka Hosszu maintained her dominance in the 400m individual medley, becoming a five-time world champion of that race, while two-time 1500m freestyle winner Gregorio Paltrinieri was beaten by Germany's Florian Wellbrock.

Zane Waddell was a surprise gold medal winner in the 50m backstroke as world record holder Kliment Kolesnikov could only take bronze behind fellow Russian Evgeny Rylov.