US swimmer Ryan Lochte bagged two golds on the opening day of the world short-course championships to add to the five medals he won in the London Olympics.
China's teen Olympic sensation Ye Shiwen finished second to Britain's Hannah Miley in the women's 400m individual medley.
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 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 women adding a third gold by winning the final race of the day, the 200m freestyle relay.