US swim star Ryan Lochte bagged two golds on the opening day of the world shortcourse championships to add to the five medals he won in the London Olympics in the summer.
The American first led from start to finish to win the men's 200m freestyle before he teamed up with Anthony Ervin, James Feigen and Matthew Grevers to win the 4x100m freestyle relay.
Lochte was pushed hard by Germany's world record holder Paul Biedermann in the 200m freestyle, but he clocked 1min 41.92sec to claim his 15th career world short course championships gold medal.
The second gold was secured in a much tougher contest and needed anchor leg swimmer Grevers to chase down and overtake Russia's Artem Lobuzov and then hold off the late charge of Italy's Filippo Magnini to secure Lochte's 16th gold medal in the championships history.
Those two golds saw the US team sit atop the medals standings at the end of day one, with the USA women adding a third gold by winning the final race of the day, the 4x200m freestyle relay.
The quartet of Megan Romano, Chelsea Chenault, Shannon Vreeland and Allison Schmitt were pushed all the way by Russia, but Schmitt's greater strength over the final 200m brought them home in front.
Elsewhere it was a good day for eastern European women. Hungary's Katinka Hosszu set a competition record of 2:02.20 when she won gold in the 200m buttefly and in doing so became the first Hungarian woman to win a medal in championship history.
Hosszu returned to the pool 30 minutes later to overhaul compatriot Zsuzsanna Jakabos in the final stages of the women's 400m individual medley and win bronze behind Great Britain's Hannah Miley and Ye Shiwen of China.
Lithuania's 15-year-old Olympic champion Ruta Meilutyte meanwhile twice broke the championship record on her way to the 50m breaststroke final. In the morning session she finished in 29.56 and then lowered it 29.51 in the semifinal.
Ryan Lochte competes in the Men's 100m Butterfly semi finals during the 11th FINA Short Course World Championships at the Sinan Erdem Dome on December 12, 2012 in Istanbul. Lochte bagged two golds on the opening day.