Russia and China continued their duel atop the medals table on the sixth day of the World Swimming Championships.
Russia boosted its leading medal totals by winning gold on Friday in the synchronized swimming duet.
Anastasia Davydova and Anastasia Ermakova's performance earned 99.084 points. Japan's silver medal duo of Miya Tachibana and Miho Takedaduo finished with 98.084, edging Spain's bronze medalists Gemma Mengual and Paola Tirados, who received 96.667 points for the host country.
Russia leads in both gold medals (five) and overall medals (10). China comes next with three golds and nine medals overall.
China took another gold in diving Friday when Guo Jingjing won the 3m women's springboard.
Guo scored 617.94 points and Russia's Julia Pakhalina got the silver with 611.58. Wu Minxia, also of China, won bronze with 589.80.
It was China's third gold, all in diving.
"We are the strongest divers in the world and we expect to get more medals in the coming events," Guo said.
In water polo, Spain and Italy were on course to defend their world titles at the conclusion of the preliminary round.
The two-time defending champion Spanish men are unbeaten in their first three preliminary-round games and the Italian women are 2-1, having lost only a tight preliminary-round match against Hungary.
The US men were 2-1-0 after beating Australia 13-7 Friday to earn a bye into the quarterfinals.
On Saturday, medals will be handed out in men's and women's 25km open water swimming, team synchronized swimming and men's 10-meter platform diving.
Away from the pool, Australia's triple Olympic gold medalist Ian Thorpe criticized the governing body of world swimming for not doing enough to rid the sport of drugs.
"I don't think it will ever be a clean championships, which is a very unfortunate thing to say," Thorpe said. "Unfortunately, this is a sport where some efforts have been made, but not enough has been done.
"I've been critical in the past and I'll continue being critical into the future until it's a clean sport."
Cornel Marculescu, executive director of swimming's world governing body, defended FINA's drug testing.
He said more than 300 athletes would be tested during the worlds, the majority coming from the pool events. He said all the winners would be given blood and urine tests.
"We have one of the best drug testing programs of any sport," he said. "We are one of the few federations doing out-of-competition blood and urine testing."
The eight days of swimming in the pool being on Sunday and the US and Australia expected to lead the medals table.
Australia has a slightly weakened team, but seems undaunted.
"In 1992 when I came to Barcelona as a rookie coach, Australia feared the US," said Australia head coach Scott Volkers. "Nowadays we don't fear them, but we hold them in the highest respect. They're a great swimming team and in my opinion they're the No. 1 nation in the world, and will remain so until they get beat in the Olympic Games. We look forward to racing them."
Guo Jingjing successfully defended her world title in women's 3m springboard to bring China its third gold medal in diving at the World Swimming Championships.
Guo scored 617.94 points and Russia's Julia Pakhalina got the silver with 611.58. Wu Minxia of China won the bronze with 589.80.
Russia's Vera Ilyina was fourth with 582.93 followed by Canada's Blythe Hartley with 575.28. American Sara Hildebrand took sixth place with 545.55 and Australia's Loudy Tourky finished seventh.