Oracle Team USA won both America's Cup races in San Francisco Bay on Monday, to close the gap with Emirates Team New Zealand.
The defenders won race 15 by 37 seconds, though Team NZ remain on match point, leading 8-5 in the race to nine wins.
Oracle's port advantage again was decisive and led through the first mark and all the way to the finish line.
Oracle earlier won race 14 by 23 seconds.
Team New Zealand says it will have to sail better if it is to win. Expecting the wind to pick up, the crew changed to a smaller sail before the second race but skipper Dean Barker admits it was a mistake.
Barker says they expected the breeze to build more than it did.
The defenders have now won the last four races.
Two more races are scheduled for Tuesday (New Zealand time).
This America's Cup regatta is now the longest in the history of the competition as it stretches to 17 days of racing.
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.
