Emirates Team New Zealand say they are very happy with the final modifications to their AC72 catamaran - and now the attention of many America's Cup observers turns to which boat Oracle Team USA will choose to defend the Cup.
"The mods have gone really well. We're really pleased," said Team NZ boss Grant Dalton yesterday. "We have sailed against Luna Rossa and having them available to do that for us has been fantastic. We will be going out again tomorrow."
The boat was rolled out of the shed on Sunday after four days of refitting - boasting two new wind enhancement modules (called spoilers though they act differently) and a new foredeck for added speed.
"The mods have helped the boat a lot; it feels better," he said, but he declined to give a percentage figure of improvement. "The data we are getting back and analysis of that indicates that we are sailing slightly better than we were.
"The flip side of that coin is that this is our final shot ... There's only six days to go and there's no more [changes] to come from us. We've gone into lockdown on that score.
"It's a shame in a way because the boats are still developing and we could probably go on developing right to the end and get faster again - but you can't keep changing it right up until racing."
It is not clear whether Oracle can say the same thing. Neither of the two Oracle boats were on the water yesterday and there is still some debate over which boat they will use - Boat 1, which has been skippered by Sir Ben Ainslie for the most part, or Boat 2, skippered by Jimmy Spithill.
Observers of the Oracle training believe Boat 2 is faster downwind and Boat 1 faster upwind - although it also seems Boat 1 has finally gone on to compliant rudders after weeks of sailing on the old, non-compliant ones.
That could be a hint that Boat 1 is coming under consideration or it could simply be that they are readying it for participation should anything happen to Boat 2.
Certainly Team NZ boss Grant Dalton believes ("I have no doubts," he said) Oracle will field Boat 2. But Oracle tactician and sailing coach Darren Bundock said recently that the choice of boat had not been made.
"Both boats have their fast points," he said. "It is just a matter of coming up with the best package. Most people expect us to use Boat 2 but Boat 1 is the fastest AC72 ever built, in my view, but it is a little bit harder to sail."
It makes for a fascinating build-up. Most of those who have consistently watched these boats on the water over the past weeks believe Team NZ are the most stable and foil more consistently.
But they also agree Oracle are very fast - and it is a question of whether they have sacrificed a bit of stability for extra speed. While the two teams seem to be converging closely in terms of speed and boat handling, they have reached this almost common point from different directions.
Emirates Team New Zealand seem to have started from a stability base and worked out how to go faster. Oracle started from a base of basic speed and have worked on adding stability - but it may be that they are worrying less about stability now to harness extra speed.
So it could come down to a battle between Team NZ's stability, smoothness and crew work versus Oracle's ability to harness a burst of speed; with Team NZ able to capitalise if Oracle make a mistake - easy in the big cats - and Oracle relying on outright pace.
That makes Oracle's choice of boat even more interesting. If the pundits are right and Boat 1 is faster upwind and Boat 2 downwind, it will make for a difficult decision in terms of the overall package. The upwind leg is the longest in terms of time in the five legs of the race and makes up about 50 per cent of the race (in time) when set against the two downward legs.
So, while upwind speed will be hugely important, it may not be the clinching factor. Team NZ's recent modifications are designed to aid their upwind speed and to keep the bows down by aerodynamic means instead of using the boards to do so.
Only time and those first two races on September 8 (NZT) will tell.
It is less of a surprise that Oracle have not named their team yet. Today the jury is set to reveal its decision in the cheating inquiry. Oracle have selected but not named their "A" racing team. The jury findings could, in theory, affect eligibility.