It's worthy of an office sweep. Place your bets on when the first collision between Team New Zealand and Oracle Team USA will come ...
It's also a worry. Oracle have two boats; Emirates Team NZ have one. If there is a mishap, Team NZ do have their Boat 1 here but, unable to afford a two-boat programme such as Oracle's, it has been cannibalised for parts for Boat 2.
If both boats are dinged in an accident, Oracle can switch straight to Boat 1. The Kiwis can also switch if the damage is severe enough but face a much bigger job to fit it out; it is also not clear how fast Team NZ's Boat 1 is compared with Boat 2.
It's an unlikely scenario, perhaps, but not impossible, especially with the aggressive style of Oracle skipper Jimmy Spithill.
One of the thrilling things about the 72ft AC72 catamarans is not just their speed but, now we are getting the close racing that Sir Russell Coutts and Larry Ellison said we would, how close they get to each other at 40 knots or more.
Glenn Ashby, Team NZ's wing trimmer, called the boats "two US$10 million carbon-fibre missiles" and never is that more clearly seen than at the start - something Team NZ will have been working on for today's races after Spithill got the better of Team NZ skipper Dean Barker in both races on Monday.
It's Spithill's style that's proving a little difficult for Team NZ - both in aggression and unpredictability. The starts today will be hugely important.
In Races 1 and 2, Spithill hurtled around at the pre-start, pulling off all manner of complicated manoeuvres. Barker kept his cool and clinically won both starts.
Plainly, Oracle rethought their start strategy. For Races 3 and 4, Spithill concentrated more in sailing in a straight line - and won both starts.
But it was Spithill's reaction in Race 2 that alarmed some observers. Nudged out at the start by Barker, Spithill attempted to go for the penalty (to slow Team NZ down), spearing his bows almost on to the hull of Aotearoa. Nothing illegal nor untoward about that, it's all part of match racing, but should anything go wrong in such circumstances, these rapid but fragile machines could do more than just suffer a few bruises.
There are rules covering such mishaps, including the ability to go to the America's Cup international jury and seek redress if a team think they have been disadvantaged by serious damage or injury. The jury can allow a team time to recover.
As well as the starts, rounding the marks - now that we are having such close racing - is also a danger zone.
It will be electrifying stuff.
This regatta is now knife-edge poised. If the Kiwis win two today, that could be an insurmountable lead or at least the establishment of a pattern that will be hard to deny. If Oracle win two, that could be a real momentum-shifter. If they win one each, as yesterday, this absorbing match will still be alive.
The score would be 4-0 (with Oracle having worked off their -2 penalty) and we would have had six races and still be unable to say who will win. Now, time to see what odds the bookies will give on a collision...
*Race 5 today, 8.10am
*Race 6 today, 9.10am
*Race 7 Friday, 8.10am
*Race 8 Friday, 9.10am