SHANGHAI (Reuters) - Hosts China and Russia, with Natalia Ishchenko taking six gold medals, dominated the first half of the world swimming championships while controversy lurked in the open water.
Russia, roared on by the crowd whose support was only marginally more vociferous for the home nation, totally outclassed the rest of the teams in the synchronised swimming, winning all seven titles on offer.
Ishchenko has now won 16 gold medals at the world championships. Only American swimmer Michael Phelps has won more world championship golds -- the Baltimore native has won 22 and begins his campaign to add to that total on Sunday in the men's 4x100 freestyle relay.
Not to be outshone, the Chinese diving machine did exactly the same in the outdoor pool just a short stroll from the main indoor venue, claiming all nine titles that had been determined by Saturday, with only the men's 10-metres platform final to come on Sunday.
The hosts, who were watched by retired NBA player Yao Ming on Saturday, are heavy favourites to emulate the Russians and complete the sweep with Qiu Bo topping qualifying for the platform final by almost 80 points.
Britain's Tom Daley, the champion from Rome in 2009, also qualified but was more than 110 points behind Qiu in sixth place.
The only other discipline in which medals were decided in the first half of the championships was the open water, held at Jinshan City Beach held about 90 minutes south of Shanghai.
Concerns about the water temperature had been raised throughout the week and were brought to a head on Saturday when U.S. officials advised their swimmers not to participate in the 25km race after they measured it at 30.4 Celsius just 30 minutes before the competition was due to start at 0600 local time.
FINA guidelines set a maximum water temperature of 31 degrees, though the German team took a reading during the race and discovered it was in excess of 32.
Bulgaria's Petar Stoychev and Ana Marcela Cunha of Brazil won the controversial men's and women's races, which were blighted by the withdrawals of several competitors before and during the events.
The world governing body, however, dismissed the complaints from some of the teams saying they had followed their protocols and new temperature limits based on a scientific study still being completed would be in place for next year.
"Personally, from the information we have, the 25 km races are successful," FINA executive director Cornel Marculescu said.
"In general, 25 swimmers pulled out. All the swimmers, we have the boat to them. They were helped into the boats in order to intervene when necessary."
Earlier in the week, Britain's Keri-Anne Payne and Greece's Spyros Gianniotis won the women's and mens' 10-km races, which also doubled as Olympics qualifiers with the top-10 finishers all earning slots at the 2012 London Games.
FINA had also conducted 115 doping tests, "seven or eight" of which had included blood tests, by the end of the first eight days, with no positive tests, Andrew Pipe, the chairman of the Doping Review Control Board said.
The main focus of action will now switch to the pool with everyone beginning their preparations for the 2012 Olympics, while all eyes will be on Phelps, who has already said next year's London Games will be his last.
"We both talked about this meet being the first step to our preparation for the London Olympic games," his coach Bob Bowman told reporters at a packed media conference on Saturday.
"What we do here will set the table of what we're going to work on and how we're going to go about working it for London."
Editing by Pritha Sarkar