SAN DIEGO – It was a day for the young on the Pacific off Point Loma Wednesday as Young America, the undefeated U.S. America’s Cup defense contender, held off an all-day attack by Dennis Conner’s Stars & Stripes to score a narrow, 18-second win and maintain its perfect record in the first round of Cup trials.

Youth was served on both sides as Conner turned over the helm to the next generation. With the 52-year-old, five-time Cup skipper kibitzing, his heir apparent, Paul Cayard, 35, steered a nearly flawless race for Stars & Stripes but never managed to crank up the speed needed to slip past the Young America.

Young America upped its record to 3-0 while Conner fell to 1-2 in this opening round of defender trials. It marked the first time in the budding Cup season that the two all-male U.S. defense entries squared off, and the level of sailing reflected the greater big-boat experience of both compared to the women’s America3 team (1-3), which had the day off.

“It’s pretty tight racing today,” said Young America sailing coach Ron Rosenberg, “unlike the last two days” when Young America beat the women’s team back-to-back. “America3’s crew work was less crisp and their tactics were average at best. We’re seeing much better racing today.”

Indeed, as Young America and Stars & Stripes battled at close quarters up and down the sunsplashed Pacific in gentle, 5- to 12-knot breezes typical of San Diego this time of year, it was hard to find a flaw in the boathandling or strategies of either.

Young America skipper Kevin Mahaney of Bangor carved out a perfect start at the gun on the left side of the starting line, where he hoped to pick up the first freshets of a budding sea breeze. The tactic worked as he poked out to a four-boat-length lead and stretched it out by staying to the left side of the course and forcing Cayard to the right as the breeze continued to build.

Mahaney led by 1 minute 2 seconds at the first turning mark, but that proved the biggest margin of the day as Cayard and Conner came roaring back. They set a large spinnaker on the next downwind leg while Mahaney’s crew set a small one. Stars & Stripes gained back half the distance to the leader before Mahaney ordered a sail change to match the big ‘chute.

From that point on it was nip and tuck America’s Cup-style racing, with Mahaney dictating terms from ahead and Cayard forcing the action from astern, pushing to as near as one or two boat lengths behind, but never getting in front.

The margins at the next four turning marks were 24 seconds, 19, 18, and 27 seconds. At the finish, Young America was met with horns and whistles from a small spectator fleet.

While Mahaney was clearly pleased with his first effort against the seasoned Conner team, he said he and his crew made too many mistakes, particularly in putting up the wrong spinnaker and giving away a good lead. “We called for the right sail but the wrong one went up,” he said.

On the challenger’s course, only one race was completed successfully as light breezes scrubbed the competition between the first two pairs that went off, neither of which reached the first turning mark in the required 50 minutes.