If Team New Zealand go on to win the 2021 America's Cup, this will be recognised as the day everything changed.
It was impossibly tense, but it all turned on a bizarre race eight when the breeze died, causing both teams to fall off their foils for long periods.
Theend result was that Team New Zealand won the second race by more than 2,500 metres, to take a 5-3 lead in the series, but that doesn't do the drama justice.
It was nerve-wracking, similar to the 2011 Rugby World Cup final, as the nation collectively froze.
Midway through the second race everything hung on a couple of tacks by Team New Zealand. Luna Rossa were marooned, floundering off their foils, victims of a breeze that had died at the top of the course.
You could feel the country holding its breath – like the final delivery in a cricket one-day international – and Team New Zealand managed the manoeuvre, stayed on the rails and eventually zoomed away from the Italians.
It was awful for Luna Rossa, who until then had sailed a wonderful race, responding to the pressure of losing the first contest of the day, when Team New Zealand had managed the first pass of the series so far.
Luna Rossa won't die wondering, but the buffer of a two-point lead rachets up the pressure as they have to win the next race, otherwise they will face match point.
It was cruel on a syndicate that has given so much but also a great tribute to Team New Zealand, who showed impressive dexterity to stay on their foils in difficult conditions.
Race eight will be remembered as possibly the most bizarre in America's Cup history. The Italians had won the start but it was tight, and they held a 16-second advantage at the first gate.
Halfway down the second leg came what was surely the flashpoint; Team New Zealand crashed off their foils, after deciding to gybe away at the last moment. They were beached, as Luna Rossa flew away. It had to be game over, as the Italians eventually built a lead of more than two kilometres. The deficit was up to four minutes at one stage, and it seemed inevitable that the series would be squared at 4-4.
But the Italians couldn't navigate the soft air just before the third gate, unable to complete their final tack. They touched down and were left submerged, while Team New Zealand gradually mowed them down. Te Rehutai eventually took the lead and there was no way back for the Italians.
Earlier we had witnessed the first pass of this America's Cup match. It was also a significant body blow for Luna Rossa, the kind of moment that is difficult to recover from.
The Italian pain was accentuated because they had made a brilliant start, probably the best of the regatta so far. Both teams were early back to the line, but a textbook move from Jimmy Spithill meant Luna Rossa roared off the line around five knots faster.
They held their lead to the boundary, but Te Rehutai was on their heels and the eight-second margin at the first gate was the smallest of the series.
Everything turned after the second gate. Luna Rossa elected not to cover, as the boats split away, then Team New Zealand benefited from what Peter Burling later described as the "last decent right-hand shift of the day."
That took the defenders ahead, and their decision to use a smaller jib also paid off. It was a procession from there, with Te Rehutai extending on every leg, as they showed their pace in clear air.
The forecast is not promising for Tuesday, with no guarantee that there will be enough wind for racing.