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Francisco Seco, Associated Press
The skipper of Artemis Racing, Terry Hutchinson, left, from the US, answers a question during a joint news conference with the skipper of the Aleph, Bertrand Pace, from France, at the America's Cup World Series Thursday, Aug. 4, 2011 in Cascais, near Lisbon. The America's Cup World Series will be held in Cascais from Aug. 6 to Aug. 14.

CASCAIS, Portugal — The latest generation of America's Cup yachts is ready to set sail in a competition that promises speed, stealth and uncertainty.

The first of three World Series events in 2011 begins Saturday off the Portuguese coast in Cascais. A new class of catamarans will streak though the Atlantic Ocean at speeds of up to 30 mph.

Eight challengers from seven nations are looking to give defending champion Oracle Racing cause for concern during the nine-day series. This marks the first step on the road to San Francisco 2013 when the American syndicate will have to defend the Auld Mug trophy in the oldest competition in international sports.