By Alden Bentley and Ronnie Cohen SAN FRANCISCO, Sept 10 (Reuters) - Embattled defending champion Oracle Team USA postponed a second America's Cup race on Tuesday, saying it needed to regroup after Emirates Team New Zealand won its fourth commanding victory on San Francisco Bay. Software billionaire Larry Ellison's American team appeared shell-shocked and asked for the time out just before the start of race two, under a rule giving the teams the right to delay one race in the 17-race series for the world's oldest sporting trophy. The so-called postponement card is generally reserved for boat breakdowns. "We feel like we need to regroup," skipper Jimmy Spithill said at a post-race press conference. "It's obvious we've got to make some changes." Oracle faces an uphill battle, having started the regatta with a two-race penalty and without its first-choice wing-sail trimmer, Dirk de Ridder. An international jury punished the team for illegally modifying its smaller, 45-foot practice catamarans in a preliminary regatta. The unprecedented cheating penalty means that for Oracle to keep the Cup it must win 11 races - two more than government-backed New Zealand. Although the score on the water is 4-1, Oracle officially lags the Kiwis 4-0 due to the infraction. On Tuesday, Oracle won the race start and cruised in its 72-foot catamaran past New Zealand to lead the first two legs of the five-leg heat, that saw average winds of 20 knots (23 mph). Then Oracle tried to do something that has never been done - to lift its foils out of the water while tacking. It bungled the rounding maneuver with a eight-second lead at the second mark, almost stopping dead, which allowed the Kiwis to close the gap. Oracle's decision to go to the right side of the upwind leg, out of the current near Alcatraz Island, also proved disastrous. The New Zealanders had better wind toward the center of the course, were able to get past Oracle after several tacks and led them by 1 minute 17 seconds at mark three. Team New Zealand finished the race 65 seconds ahead of Oracle. "The boat is going really well upwind," Kiwi skipper Dean Barker said after the race. "It's working for us." But he said he had no intention of laying back. "There's no easy races," he said. A breakdown now could be devastating for Oracle, which can no longer postpone and needs to win another 10 races, while New Zealand needs just five more wins. Spithill continued to express confidence that his team could keep the 162-year-old trophy. "It's not over," he said. "As a team, we've come back from a lot of adversity. This doesn't worry us. We've been here before, and it's just a matter of getting back working again." Asked what he would change, Spithill said everything was on the table - from sail changes to crew changes. Asked if he was concerned about his job, he responded, "You can be a rooster one day and a feather duster the next day." Emirates Team New Zealand won three of the first four races. But, after a shaky start, Oracle Team USA charged back with a vengeance on Sunday, leading much of the third duel, winning the fourth and proving itself a formidable competitor. The radical 72-foot catamarans looked evenly matched in Sunday's racing and overall the competition has been more exciting than many expected, featuring dramatic starting maneuvers, near collisions, lead changes and closely fought tacking duels. The cheating scandal, quarrels over rules and grief over the death of a sailor during a training exercise took center stage during the preliminaries, when a promised "summer of racing" to determine which yacht could take on Oracle fizzled into a lopsided series with powerhouse Team New Zealand dominating. Now the TV network-dubbed "September Showdown" is delivering high-adrenaline, edge-of-the seat racing in San Francisco Bay's natural amphitheater. Flag-waving fans have watched in awe along the waterfront as giant twin-hulled yachts with three-story tall wing sails cross within inches of one another, and scream into the finish line on hydrofoils barely a stone throw from the America's Cup pavilion. The yachts look like airplanes flying when their foils lift the hulls out of the choppy water. With 11 sailors on board, the yachts have cruised as fast as 53 miles an hour around the five-leg race course, starting near the Golden Gate Bridge, sailing past Alcatraz Island and finishing against the backdrop of the San Francisco Bay Bridge. Ellison and his crew desperately want to keep the Cup. But the Kiwi team has vowed to bring the Auld Mug, as they call it, back to its Royal New Zealand Yacht Squadron. Team New Zealand held the trophy from 1995 until 2003 with the Kiwi sailor Sir Russell Coutts at the helm. He now runs the Oracle Team USA. The 51-year-old Olympic gold medalist has won the America's Cup four times, twice for his homeland. Ellison chose the 72-foot catamarans as the boats and his home waters of San Francisco Bay as the venue for this year's competition. Critics complained that the boats were too fragile and hard to handle after Olympic gold medalist Andrew Simpson of Britain was killed in a May training exercise for Sweden's Artemis Racing.