Team New Zealand up on their foils during America's Cup training in Bermuda.

Team New Zealand have hooked up with British syndicate Ben Ainslie Racing for an informal drag race in Bermuda, and the Kiwis certainly didn't have it all their own way.

Another round of practice racing is under way on the Great Sound ahead of the official challenger qualifying series that starts on May 27.

The Kiwis aren't involved in the current practice racing, though there is speculation they may join the final day of this round on Saturday.

SUPPLIED Ben Ainslie Racing on their first day on the water in Bermuda, in December 2016.

But with so much action on the water as the Kiwis trained again on Wednesday (NZ time), it didn't take long for Ben Ainslie Racing to come alongside and look for a brief duel in 15-20 knots of wind.

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Team New Zealand's five rivals have been desperate to get a handle on the Kiwis and their pedal-powered boat, just as Glenn Ashby's crew have been eager to get a feel for their opponents.

The Brits have been one of the strugglers over the early practice racing period, but video surveillance showed they looked pretty comfortable against the Kiwis, appearing to have a slight edge in speed and they didn't lose much as they followed Team New Zealand into a sharp foiling tack.

Team New Zealand are still going through a testing phase having just reassembled their AC50 and got it into the water on Sunday.

Who knows how much of this is shadow boxing and what's being held back?

The Kiwis are still using their test foils and can expect significant improvement when their full racing hardware is used.

Team New Zealand had a large red poppy attached to their wingsail to commemorate Anzac Day.