Oracle Team USA helmsan Jimmy Spithill says Team NZ have made "fundamental mistakes" in both of the races between the two boats.

America's Cup veteran Paul Cayard has questioned the match-racing skills of Team New Zealand helmsman Peter Burling as the spotlight goes on the Kiwi's scratchy work in the starting box and in confrontational situations on the course.

Team New Zealand emerged as the top challengers from a tough round-robin schedule in Bermuda that provided as many questions as answers amongst a competitive fleet.

But Team New Zealand's meltdown against Oracle Team USA in their last round-robin clash when a vital bonus point for the eventual America's Cup match was on offer, has brought increased inspection of the Kiwi syndicate.

EMIRATES TEAM NZ Team New Zealand helmsman Peter Burling looks for options rounding a mark as Oracle Team USA heads away looking to increase their lead.

American Cayard, a respected figure who was involved in eight America's Cup cycles from 1987 to 2013, felt ruthless Oracle skipper Jimmy Spithill had exposed a weakness in Team New Zealand again.

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Oracle was the only boat to beat Team New Zealand in the round-robin racing, managing that twice with their second win coming in a genuine pressure situation with plenty at stake.

"Jimmy Spithill schooled the young talent, Peter Burling, at the start giving the Kiwis a penalty," Cayard, who lost the 1995 Cup match to Team New Zealand in San Diego, wrote in his race analysis for Sail-World.com.

"I think this is the Kiwi's weak point. In all boat on boat situations, the Kiwis come out worse than their opponent.

"When they are free to sail in the open, there is no one faster or steadier in their boat handling."

REUTERS Paul Cayard has that sinking feeling as he helms Stars and Stripes in their 1995 America's Cup final loss to Team New Zealand.

Cayard outlined two sailing situations on the course, rather than the starting box, that highlighted some shortcomings in Team New Zealand's work in that costly defeat last Sunday.

"The Kiwi's made some gains upwind and Oracle even ducked them once. But Oracle, coming back on starboard tack, made the Kiwis tack very close to the windward mark and simply rolled through to leeward and sped off to a huge lead," Cayard, who has won the Star class world title and been a successful offshore sailor including winning the Volvo Ocean Race, wrote.

"On the second windward leg, Oracle pushed the Kiwi's into the lower right corner by tacking on them. This produced a 200 metre gain at the next cross. Game over."

GETTY IMAGES Paul Cayard, left, in his role as boss of Artemis Racing's ill-fated 2013 challenge, discusses the America's Cup with Sir Russell Coutts.

The intricacies of match-racing always loomed as a key area for Burling, whose superstar status in sailing has been built around his successful fleet racing in the Olympic 49er skiff class.

While the incredibly fast foiling 50-foot catamarans being used in Bermuda provide opportunities and challenges of their own, some basic match-racing principles remain in play.

Team New Zealand have lacked those under heat from Spithill in both their losses to the outspoken Australian who leads the American defenders.

That will be a huge area of work for the Team New Zealand coaching team of Rod Davis and Murray Jones now.

Refining the afterguard work and getting the best out of skipper Glenn Ashby and tactician Blair Tuke working alongside Burling will be vital from here.

The decision to reduce the crews from 11 to six between San Francisco and Bermuda has brought challenges to the systems of the afterguards for all the syndicates. There is no longer a dedicated tactician free to roam the trampoline keeping an eye on the opposition, race opportunities and windshifts. The tactician is now also required to provide plenty of grunt work on the grinding machines and for Tuke that means assessing while cycling.

Team New Zealand clearly have a fast boat across a range of conditions, and look particularly effective in the lighter airs that could dominate the business end of the regatta.

The starting problems are understood to be one reason whey they have chosen Britain's Ben Ainslie Racing as their opponent for the challenger semifinals.

In a risk versus reward scenario, Ainslie had the greater appeal.

Ainslie has what looks to be the slowest boat of the four remaining challengers and is therefore the weakest link.

But he has proven the most successful skipper off the start line and will provide Burling plenty of learning opportunities over their best of nine semifinal series.

The opening day to that series was called off on Monday (NZ time) as lights winds dogged the regatta for the second time in just over a week.

The four races were were moved to Tuesday's scheduled lay day.

Tuesday's schedule for Louis Vuitton America's Cup challenger semifinals

5.08am: Race 1: NZ vs GBR

5.37am: Race 1: Sweden vs Japan

6.06am: Race 2: GBR vs NZ

6.35am: Race 2: Japan vs Sweden