By Rod Gilmour
BUDAPEST (Reuters) - Sun Yang of China was a notable absentee at the world championships on Saturday after he failed to start his men's 1500 meters freestyle heat at the Duna Arena.
Although the 25-year-old trained in the pool on Saturday morning and is expected to compete in the men's 4x100m medley on Sunday, the Chinese Swimming Association confirmed his decision to sit out the 1500m race.
"Sun competed in several events with high intensity here during the past day. For the sake of his health and preparations for the Tokyo Olympic Games, Sun has decided to withdraw from the 1500m contest here," the Chinese Swimming Association said in a statement.
Sun's bid for a clean sweep of freestyle distance titles ended when he was beaten out of the medals in the 800m freestyle.
That setback followed Sun striking gold in the 200m freestyle and then completing a hat-trick of freestyle world titles over 400m.
Saturday's withdrawal means that Sun, the London 2012 champion, has now failed to contest the last three global 1500m freestyle finals.
At the 2015 championships he was a shock withdrawal on medical grounds minutes before the final. At the Rio Olympics, he failed to qualify for the medal race.
In the 1500m heats here, Ukraine's Mykhailo Romanchuk posted the fastest time ahead of Sunday's final, with 14 minutes 44.11 seconds.
Denmark's Pernille Blume predicted she could go faster after she coasted through to the women's 50 meters freestyle semi-finals.
Sarah Sjostrom, who missed out on gold in the women's 100m freestyle, topped qualifying to lead a Scandinavian one-two in the one-length dash. The Swede posted 24.08 seconds.
"It was a fine feeling for me. It was a powerful swim but I didn't sprint at all," said Blume, who touched 0.24 seconds behind Sjostrom.
In the men's 50m backstroke, a relaxed-looking Camille Lacourt of France posted the second-fastest time in preliminaries behind Japan's Junya Koga.
Koga clocked 24.54 seconds while the Frenchman finished 0.04 seconds behind.
Lacourt will retire from swimming on Sunday, with the 32-year-old bidding for a hat-trick of 50m world titles.
He admitted that he had only been training for 15 minutes each day in the build-up to the championships.
"I haven't prepared well," said Lacourt, who opened a cocktail bar and restaurant in Paris in May.
In the women's 50m breaststroke, American Lilly King posted a swift 29.76 seconds, qualifying ahead of Russian rival Yuliya Efimova.
Meanwhile, the Netherlands will enter the mixed 4x100m freestyle final later on Sunday as the gold medal favorites after posting three minutes 23.89 seconds.
(Editing by Pritha Sarkar)