And the man credited with the astonishing turnaround is British Olympic legend Ben Ainslie, who was drafted in to be the US team's new tactician when they were trailing 4-1 and seemingly already doomed to defeat.
The stunning recovery for the team backed by Oracle co-founder Larry Ellison continued on every front in perfect sailing conditions Tuesday. The US boat came from behind to win the second race easily and has now has seven straight victories, another Cup milestone.
New Zealand dominated that start for the first time in recent races, but then committed several tactical errors and Oracle stormed to a lead of nearly a minute at the finish.
In the first race the reeling Kiwi team drew a double-penalty as the two boats crossed the starting line, which allowed Oracle to jump to an insurmountable lead.
New Zealand once led the competition 8-1, and numerous Kiwi fans in San Francisco and back home in New Zealand were ready to celebrate victory in a gruelling two-year-long Cup campaign. The New Zealand government contributed about $30 million to the effort to bring the Cup back to the sailing-crazed nation.
But boat improvements, superior tactics and sharper sailing by Oracle have turned its fortunes around, evidenced in the second race Tuesday when the team appeared to show more speed on every leg of the race.
“I didn’t consider I would be racing in this event so it is a real bonus and privilege,” said Ainslie, who set up his own team earlier this year in order to challenge for the next America's Cup.
But it seems that the four-times Olympic champion may get his hands on the trophy quicker than he ever imagined.
“I’m really excited about being out there, getting closer and closer to winning this event. I’m loving it.”
It's not just the tactics of Ainslie and his fellow sailors that has led to the turnaround: improvements to the yacht have also been important, according to Oracle skipper Jimmy Spithill.
"We've been doing a lot of work at night with design engineering technicians," Spithill said after the first race. "The boat is just going faster and faster and the boys are really starting to believe."
New Zealand skipper Dean Barker acknowledged in comments after the races that Oracle was now faster on the upwind legs in heavier winds. New Zealand pioneered the so-called "foiling" in which the big boats lift almost completely out of the water and sail on small horizontal wings attached to their daggerboards and rudders, but Oracle is now doing it more effectively on the critical upwind leg.
"It's the first time we've seen conditions where we were not as good as we needed to be," said Barker.
Spithill had put on a brave face through the early losses, insisting that the event was "far from over" even when his team needed an implausible nine straight wins to keep the oldest trophy in sports. His bravado, backed by consistently shrewd manoeuvres at the start, has now been vindicated.
"There's a huge wave of momentum we've been riding and it just builds and builds and builds," Spithill said after Tuesday's victories.
Barker sailed nearly flawlessly for much the summer as the Kiwis trounced Italian and Swedish challengers for the right to race Oracle. His dominance continued in the early races of the final as the Kiwis showed better speed upwind and much smoother tacking.
But the team has appeared to come apart in the face of the Oracle comeback and a run of bad luck that saw two races in which it was leading called off due to wind conditions.
The start of Tuesday's first race featured classic match-racing drama. New Zealand miscalculated and bumped Oracle, which had the right of way, as it maneuvered to block its rival on the approach to the line.
The two 72-foot catamarans made contact again as they drifted across the line. A second foul was called on the Kiwis, which had stopped dead in the water as Oracle sped off to a large lead around the first mark.
New Zealand used textbook starting tactics in race two to get a solid lead around the first mark. But Oracle gained ground going downwind, and, after New Zealand mistimed a tack as the boats converged on the upwind leg, foiled past the Kiwis to open a big lead.
The regatta was supposed to be over on Saturday, but racing has been postponed several times for too much wind, not enough wind and wind from the wrong direction, dragging the event out into a third week. Rule changes lowered the wind limits after the Swedish team suffered a fatal training accident in May.
A two-race penalty against Oracle for illegal boat modifications in a preliminary regatta has also lengthened the competition. Oracle has actually won 10 races on the water, but only 8 of them count.
New Zealand yachting fans are now left to wonder whether Barker and his team can take a page from Oracle's book and find a way to win with their backs to the wall.
"I'm struggling to keep positive. My faith in the team and Dean is being sorely tested. We're only one (win) away, but my nerves are a bit like our chances, in tatters," said Wellington office worker Will Christie.
Ellison skipped a keynote address at Oracle's massive annual customer conference on Tuesday to be on San Francisco Bay as his team fought its way to the match point tie with the Kiwis.