Yesterday Team New Zealand rocketed out of the blocks taking an early 1-0 advantage in their first-to-seven series off Bermuda.
The challengers quickly erased the defenders' one-win advantage on the scoreboard - a result of Oracle's win in the challenger qualifying series earlier this month - and built their own lead with victory in the day's second race.
It was an almost totally dominant display from Emirates Team NZ helmsman Peter Burling, who had the better of counterpart Jimmy Spithill throughout the opening exchanges, winning both starts and overcoming slight lapses late in both races.
Both ACC boats were even off the start-line in Race Two, but Team NZ built superior speed to the first mark and quickly extended to more than a minute in front at the third gate.
Oracle made huge gains up the fifth leg and were within a couple of metres rounding the top mark, but immediately fell off their foils on a gybe and lost several hundred metres in the space of a few seconds.
That error cost the American syndicate any chance of overhauling their rivals.
"Fantastic rally from the boys, particularly the guys forward today - just a massive effort on the hydraulic front," reflected Team NZ skipper Glenn Ashby.
"It's so shifty and so puffy, as we saw out there ... you never stopped trimming something for the whole day, so those guys got an absolute whipping today.
"We made a few mistakes around the track obviously, but so did the other guys, so one of those days where it was pretty hard to string every single puff and every single shift together."