Team New Zealand's rivals now have the benefit of early official practice racing in Bermuda after a late rule change.

Another late change to the America's Cup protocol has been stacked against Team New Zealand.

Their five rivals have used their majority vote to now allow teams to have 23 days of training against each other in their official Cup catamarans in Bermuda in the leadup to the first official races that start on May 27 (NZ time).

The first practice races have already begun with video footage emerging of America's Cup holders Oracle Team USA and British syndicate Ben Ainslie Racing duelling.

An oversight in the protocol had previously barred that, happily noted by Team New Zealand as they continued to work away in Auckland on their build and development.

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The latest change will restrict any involvement Team New Zealand will have in this practice racing because of the Kiwi syndicate's schedule.

As time ticks away, the practice window will slowly close on Team New Zealand who are only due to head to Bermuda early next month.

The latest development was dryly noted by Emirates Team New Zealand in a Facebook posting, saying: "America's Cup Class race boats lining up already? Until this week it was prohibited by the protocol, but now allowed after yet another rule change. Working together to protect their future AC framework agreement?"

The development further emphasises the dangers Team New Zealand face operating in their "lone wolf" status.

Team New Zealand have been opposed to many of the developments in this cup cycle but have been powerless to stop it. They don't like the recent decision to extend the current rules and format for the next two editions of the Cup beyond this year's event in Bermuda. If the Kiwis win in Bermuda, they would likely use their power to return to the regatta to the traditional format under the Deed of Gift.

"The danger of being a lone wolf, of course, is that there's a lot of people, not just Oracle, that don't want us to win this time," Team New Zealand boss Grant Dalton said earlier this month.

"There are five teams that want us dead now, not one, only because we've ruined their little parade."

Team New Zealand have gone out on a limb with their design that has them using pedal-power.

The latest rules adjustment conveniently allows the design and development arrangement between Oracle and late entry Team Japan to continue but goes beyond that.

Just how much teams will want to reveal in the practice racing remains to be seen. There will certainly be plenty of "shadow boxing" going on.

But the opportunity to execute manoeuvres under pressure in race conditions is certainly beneficial and something Team New Zealand, for the moment, can't enjoy as they operate solo on the Waitemata Harbour.

In the meantime Team New Zealand will have to rely on their reconnaissance to keep them up with play in Bermuda.

Other unexpected changes that have happened during this cycle include the reduction of the size of the catamarans that saw Italians Luna Rossa withdraw in protest, and rules governing replacement daggerboards.