The challengers from New Zealand had two sails come unstuck today in the fifth race of the America's Cup, giving defending champion Alinghi a 19-second win and a 3-2 lead in the best-of-nine series.

"The pressure's on now _ it's a very close contest between two very close teams and two close boats," Alinghi sail trimmer Simon Daubney said. "One little slip-up can be very costly."

Emirates Team New Zealand led the Swiss down the start of the second leg and was about to change its damaged spinnaker when a strong breeze ripped the lightweight sail in half.

The NZL-92 crew raised a new sail as it cut down the damaged one, but the new one failed to set in place.

"At this stage, I think you could say that there was a slight breakdown in communications," New Zealand crew member Grant Dalton said.

By the time a third sail was in place, Alinghi had sped past for a lead it would not relinquish despite an intense race to the finish.

"These regattas are tight and you have to get it dead right," Dalton said. "Alinghi's getting it dead right."

The sixth race for the Auld Mug, the oldest trophy in international sports, is scheduled for Saturday.

The Kiwis made a strong start _ in conditions expected to favor the Swiss team's boat _ but got into serious trouble on the first downwind lap. The boat's red kite dramatically blew apart, seconds after the yacht bounced off a large wave, as the Kiwis were preparing to switch it after noticing a small hole near the top.

The newly hoisted sail failed to set in place, flapping off a single rope atop the mast and forcing the crew to hoist a third sail that got tangled up in itself.

"At that point, it was chaos," Dalton said.

The Kiwis had two unresponsive sails _ and the Swiss raced past.

When the third sail finally set and the second one fell away into the water, the New Zealand boat put on some pressure _ but could not catch up.

Alinghi's second straight win put the Swiss back in control of the closest series in 24 years.

"I won't be pointing fingers because there's none to point. Every team has to be tough on itself because it only makes you stronger," Dalton said. "How you react to these things is how you move forward."

Stronger wind conditions were expected to favor the SUI-100 boat, but the NZL-92 yacht rounded the first marker with a 12-second advantage.

Team New Zealand's kite failure handed Alinghi a 26-second advantage around the second buoy. The margin was reduced to 24 seconds around the final marker, but Alinghi skipper Brad Butterworth coolly covered each Kiwi move down the final run to maintain the lead.