Larisa Ilchenko surged to defend her world champion title in the 5km open water swim and to clinch the opening gold at the Championships in Melbourne.

Ilchenko was the hot favorite to triumph as the 18-year-old had won this event at every FINA World Championships and World Open Water Championships since 2004.

Although Kate Brookes-Peterson from Australia led for quite a long time, Ilchenko never lost her pace, managed to swim almost side by side and surpassed the host rival with strong strokes in the final meters.

Ilchenko clinched the gold in one hour and 41.3 seconds. Her compatriot Ekaterina Seliverstova, who also surpassed Brookes-Peterson at the end, finished second in one hour and 43.6 seconds.

Brookes-Peterson, completing the event four seconds behind Seliverstova, grabbed the host's first medal in the 16-day Championships.

The prolific Russian team led the preliminary on Saturday with 99.00 points and earned the same score in Sunday's final to collect the gold.

Traditional powerhouse Japan won the silver with 97.833 points and the United States finished third at 96.500 points.

The other gold produced on Sunday was grabbed by German Thomas Lurz. The 28-year-old veteran clinched the title of the men's 5km open water swim at 56 minutes and 49.6 seconds, narrowly edging Evgeny Drattsev from Russia, who finished 1.1 second slower.

It was Lurz's third straight world title as he had won in the 2005 Montreal World Championships and the 2006 World Open Water Swim Championships in Naples, Italy.

Athens Olympics 1,500 meters freestyle finalist Spyridon Gianniotis from Greece took the bronze medal at 56 minutes and 56.6 seconds.

The solo free routine preliminary was also held on Sunday. Dual world champion Virginie Dedieu from France led the field of 28 at 99.00 points. She is going to contend with the other 11 finalist next Thursday.

Two diving finals and one synchronized swimming final are slated to show on Monday. China is likely to sweep the golds of men's three-meter springboard and women's 10-meter platform diving, while Russian Natalia Ischenko is the hot favorite to win in the solo technical routine event.

The women's water polo competition also kicks off on Monday. The defending champion Hungary is going to fight against Italy.