Oracle Team USA won race eight of the America's Cup by 52 seconds on Sunday after Emirates Team New Zealand nearly capsized on the upwind leg.
After narrowly winning the start, Team New Zealand led by three seconds at mark one, but fell behind after almost tipping over on the third leg.
Team New Zealand incurred a penalty and lost the lead.
''We had one tack, which was a routine tack, and we didn't get the hydraulics," Team NZ skipper Dean Barker said in a televised interview afterwards.
''If the wing doesn't tack and the boat does, you end up in the drink,'' he said. ''Fortunately the boat came back up and there was no collision with the other guys."
"Man, I thought that was close to going," said Oracle skipper Jimmy Spithill afterwards. "We got ready for a crash tack."
Oracle led by 28 seconds by the time Team New Zealand rounded the third gate and crossed the finish line 52 seconds ahead.
The victory was Oracle's second of the regatta, erasing a two point penalty for cheating in a preparatory event.
The challengers still lead the series by six races.
The second race of the day, race nine, was called off after the wind limit of 30 knots was reached. Team NZ won the start and held the lead until then.
Lower wind limits were imposed after a British sailor was killed in a capsize of the AC72 craft sailed by Artemis Racing in May.
Another two races are scheduled to be held on Monday (New Zealand time).
In Auckland, Royal New Zealand Yacht Squadron Vice Commodore Andy Anderson said Oracle showed they are not going to give up.
While he remains confident that Team New Zealand can win the trophy, Mr Anderson said they need to take it one race at a time.
An American yachting journalist says Oracle faces an uphill battle to win the America's Cup.
Jeff Bell of KCBS News in San Francisco said Team New Zealand has captured the imagination of people in San Francisco and sailors there believe Oracle cannot (now) win.
If it wasn't for the prospect of the America's Cup leaving San Francisco, he said, people would be cheering for Team New Zealand.
The winner of the event will choose the venue and format of the next America's Cup.
New Zealand first won the Cup in 1995 and successfully defended it in 2000 before losing the trophy to Alinghi in 2003. Oracle won the Cup in 2010.
The America's Cup was first contested in 1851 around the Isle of Wight. The race was won by a US yacht, America.