China's Ye Shiwen can expect a battle royal in the women's 200m individual medley final on Monday evening, as the reigning champion defends her title at swimming's world championships.

The 17-year-old was the second-fastest qualifier on Sunday behind Hungary's Katinka Hosszu, who clocked 2mins 08.59 in Sunday's semi-finals, with Australia's world silver medallist Alicia Coutts third quickest.

"It's definitely going to be a great race. We will be pushing each other but it won't just be about us two because others will go much faster in the final," said Hosszu, the 2009 world 400m IM champion, of her rivalry with Ye.

South Africa's Cameron van der Burgh will also be looking to add the world title to his Olympic crown in Monday's final of the men's 100m breaststroke with Australia's Christian Sprenger, who won silver in London, the fastest qualifier.

In the women's 100m butterfly final, Coutts, who races in two finals on Monday night, will be amongst those challenging Olympic champion and world record-holder Dana Vollmer.

Teenager Ruta Meilutyte, who won the Olympic 100m breaststroke title as a 15-year-old in London, stormed through Monday morning's heats, setting a new championships record of 1min 04.52, ahead of the evening's semi-finals.

"It's not a problem, because I have enough energy for the whole competition," beamed the 16-year-old Lithuanian, who said she was unconcerned about charging out in the heats.

Missy Franklin of the United States was the fastest into the Monday night's 100m backstroke semi-finals from the morning's heats, with Hosszu just behind her.

The 18-year-old Franklin, who won four Olympic titles in the London 2012 pool, is competing in eight events in Barcelona and won her first world gold on Sunday when the USA won the women's 4x100m freestyle relay.

"It feels really good, I obviously got things started last night and the 100m backstroke is the perfect event to come off the relay into," said Franklin.

The teenager is closing in on the four-year-old world record of 58.12secs for the women's 100m backstroke.

"I haven't thought about it (the world record), I'm just going to go out there, swim and have fun," she added.

"When you reduce it down to a number, you lose what it's all about."

Franklin is bidding for eight gold medals including the 50, 100, and 200m backstroke, 100 and 200m freestyle and two more relays.

Katie Ledecky, the US teenager who just missed the world record in winning Sunday's 400m freestyle final, was back in the pool Monday morning as the second fastest qualifier for Tuesday's 1500m freestyle final.

Denmark's Lotte Friis, the 25-year-old defending world champion, was fastest in 15mins 49.18 but Ledecky was just eight hundredths of a second behind her.

"I've definitely got a lot left in the tank, I just carried the excitement and energy from last night into this morning," said Ledecky.

In the morning's heats for the men's 100m backstroke, both Olympic champion Matt Grevers of the United States and France's defending world champions Jeremy Stravius and Camille Lacourt, who shared the 2011 gold in Shanghai, qualified for the evening's semi-finals.

Australia's Ashley Delaney was the fastest into the semi-finals, clocking 53.60secs with Stravius, Grevers and Lacourt in the top 10.

In the men's 200m freestyle, Olympic champion Yannick Agnel of France and defending title holder Ryan Lochte of the United States both qualified for Monday's semi-finals with Britain's Robbie Renwick the fastest, clocking 1min 46.88secs.

Japanese teenager Kosuke Hagino, 18, who won world silver on Sunday in the men's 400m freestyle final, was fourth fastest, having also qualified seventh fastest in the men's 100m backstroke as he races in five individual events.