As both teams jockeyed for position down the third leg, TNZ tacked the better and moved past their archrivals to build a 20-second buffer by the next mark.
But down the fifth leg, the Americans came back strongly and almost drew contact with the NZ boat, as they rounded the fifth mark. That proved the crucial moment, with Oracle easeing away for a six-second win.
Both Emirates Team NZ and Oracle warmed up for their showdown with easy wins over France, one of the lesser fancied teams in the qualifier series.
The Kiwis were two minutes 33 seconds better than the French, while USA were two minutes 11 seconds clear.
Rookie TNZ helmsman Peter Burling gave wily French counterpart Franck Cammas a sailing lesson, controlling the start and rocketing away to lead by one minute 13 seconds by the third mark.
By contrast to their opponents, Team New Zealand sailed a smooth race, staying on their foils through most of their journey to cross the finish line before France had even rounded the final mark.
"It's good to have our first race under our belts," said TNZ skipper Glenn Ashby, the only survivor from the ill-fated 2013 challenge in San Francisco.
"The boys sailed the boat very nicely. It's really nice to be out here on the Great Sound.
"Everyone is going to learning a huge amount over the next few races. We haven't done a huge amount of yachting in the last coupe of weeks, so our learning curve will be pretty steep."
The French had already been on the water earlier in the day, providing little opposition for Oracle.
For the first time, the defenders have been allowed to contest the challenger series as part of their build-up and Oracle showed they were already on the money.
Aussie skipper Jimmy Spithill had Oracle seven seconds ahead at the first mark and 15 up by the second, steadily increased their advantage as the race progressed.
The American team took nearly 40 seconds out of their rivals on the third leg and showed far greater control of their AC50 boat in perfect sailing conditions. While yesterday's scheduled opening day was cancelled due to winds in excess of the 24-knot upper limit, today provided 9-10 knots, ideal for foiling.
Oracle also made a fascinating call on their choice of equipment, using non-identical foils for the first time in America's Cup racing.
"Perhaps this wind strength is around the crossover for their foils and so it's not a big deal which set they use and they like the advantage of having the stronger wind foil on the port side for the first reach off the start, when they travel at higher speeds," suggested NZME America's Cup commentator and former Team NZ weather guru Mark Orams.
Day one results:
Oracle Team USA bt Team France delta - 2m 11 s
Artemis bt Team Japan delta - 13s
Emirates Team NZ bt Team France delta - 2m 33s
Ben Ainslie Racing bt Artemis - 11s
Oracle Team USA bt Emirates Team NZ - 6s
Team Japan bt Ben Ainslie Racing - 48s
America's Cup Qualifiers leaderboard
Oracle Team USA - 3pts (1 point carried over from ACWS)
Ben Ainslie Racing - 3 (2 points carried over from ACWS)
Artemis - 1
Emirates Team NZ - 1
Softbank Team Japan - 1
Groupama Team France - 0
