AUCKLAND, New Zealand -- Oracle of San Francisco and Alinghi of Switzerland won close races as the protest-filled America's Cup challenger quarterfinals began Wednesday.

Top qualifiers Alinghi beat Prada of Italy by 1 minute, 18 seconds, after leading by only eight seconds at the final mark. Oracle beat OneWorld by 12 seconds.

Britain's GBR Challenge sailed past New York's Stars & Stripes to win by 1 minute. Stars & Stripes led around all five marks by up to 55 seconds but carried a penalty throughout the race. The British yacht's margin was inflated when the New York team completed that penalty at the finish.

Sweden's Victory Challenge beat Le Defi of France by 2:03 in the day's only one-sided race.

Racing was delayed two hours Wednesday by light winds but the quarterfinals started in a breeze of between 14 and 19 knots.

OneWorld carried a penalty from the second leg of the race, when, as it gibed toward the bottom mark, it failed to allow Oracle room to keep clear. Oracle was already flying a red flag in protest over an incident earlier in the race.

OneWorld discharged that penalty by completing a 270-degree turn as it approached the final mark, giving up the lead to Oracle, which rounded 14 seconds in front. Although OneWorld closed to within meters on the final run, Oracle maintained its composure and its lead.

Prada earned a penalty when its bow touched Alinghi's stern as the boats sailed in each other's shadow down the first run.

Alinghi led around the first three marks by a peak margin of eight seconds but Prada gained the lead on the second downwind leg, rounding the bottom mark 13 seconds ahead.

The Swiss team regained the lead on the next leg to windward and was eight seconds ahead, with Prada still under the burden of its penalty, as the yachts turned for home.