Katie Ledecky’s bid to become the first swimmer to win four individual freestyle titles at a world championships remained on track as the American claimed a stunning gold in the women’s 200 metres.

After qualifying for the final in seventh during a punishing schedule which meant Ledecky raced her semi-final 30 minutes after winning the 1,500m freestyle gold with a world record, the 18-year-old American touched first in one minute 55.16 seconds.

Ledecky’s win, achieved from lane seven, added to her golds in the 400m freestyle on the opening night and the 1,500.

Sun Yang of China dug deep, also from lane seven, to win his second gold, the men's 800m freestyle, after a thrilling battle with Italy's Gregorio Paltrinieri.

Briton Adam Peaty continued his fine form by adding the men's 50m breaststroke gold to his 100m breaststroke title.