<div><p>VALENCIA, Spain (Reuters) - Race organizers sounded a warning note on the eve of the 33rd America's Cup on Sunday, saying the size and potential speeds of the two boats posed problems never encountered in the event.</p><p>The massive multi-hull yachts of Swiss holders Alinghi and U.S. challengers BMW Oracle are capable of speeds in excess of 30 knots but neither has ever raced before.</p><p>They square off for the first time in Monday's opening race of the best-of-three series off the Spanish port of Valencia after more than two years of sometimes bitter legal wrangling between Alinghi and software billionaire Larry Ellison's team.</p><p>"We're 100 per cent focused. The only thing we're thinking about now is winning two of the next three races," Ellison said on the Cup's Twitter page late on Sunday after refusing to attend an owners' media conference the previous day.</p><p>The huge course -- an upwind leg and a downwind leg totaling 40 miles -- mean the start line could be set anywhere between 25 and 40 miles off the Valencia waterfront. Exclusion zones have been established to give the 90-foot yachts room to maneuver.</p><p>"No one has ever seen these boats race together before," regatta technical adviser Sebastien Destremau said.</p><p>Of particular concern will be the start line -- anywhere between 600 meters to 1 km long -- as the two yachts converge for the starting gun shortly after 10 a.m. (0900 GMT).</p><p>Pre-race maneuvers in such events are usually aggressive but the size and novelty of the boats add extra elements of danger.</p><p>"Tomorrow morning ... we will see these two monsters coming toward each other head on. Anything could happen," Destremau told reporters.</p><p>Destremau said the boats were capable of speeds of up to 15 knots downwind and between 35 and 40 knots upwind.</p><p>STRICT RULES</p><p>The potential speeds have resulted in strict rules governing race conditions, with no racing in winds above 15 knots or in seas with waves higher than one meter.</p><p>Monday's weather forecast is for winds from the southwest of 6-10 knots, with gusts of up to 14 knots.</p><p>Both boats had their final day of training on Sunday in conditions similar to those expected on Monday. "We had a very good sail," said BMW Oracle chief executive Russell Coutts, who may helm the boat on Monday.</p><p>The America's Cup has traditionally been contested by monohull yachts with less restrictive rules but more than two years of legal wranglings have resulted in a number of firsts.</p><p>Holders Alinghi have designed a hi-tech catamaran as wide as two tennis courts placed side by side and with a tilting mast towering 17 storeys high.</p><p>BMW Oracle's trimaran USA is equal in size to two basketball courts and has a unique wing-shaped mast larger than the wing of a commercial jetliner.</p><p>(Editing by Justin Palmer)</p><img src="http://admatch-syndication.mochila.com/images/ad.gif?aid=68642591&bid=informcom" /></div><div id="copyright"><div>

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