Luna Rossa ace Jimmy Spithill believes conditions will play a huge part in dictating the America's Cup outcome.

Spithill has downplayed the significance of reports about Team New Zealand reaching extreme speeds in Te Rehutai, saying past experience told him reconnaissance was often unreliable.

And in an interview with Newstalk ZB's Mike Hosking, Spithill has also paid TNZ skipper Peter Burling the ultimate compliment, describing him as the "best in the world".

"I think it could come down to conditions from what we saw in the Christmas Cup," Spithill said.

"They had a pretty powerful package from the mid-range up. We've seen from the round robin and [Prada Cup] final series that our boat has been going pretty well at the bottom end of the conditions.

"We've both been working hard at where we are vulnerable.

"It will be really interesting to see who has bridged the gap and got a little bit more crossover from where they were potentially weaker against the other team."

Spithill said Auckland's lockdown had changed little around the base, but there was a big difference on the harbour which had been emptied of boats.

"We really do have the whole harbour to ourselves," he said.

"The only boat we do see is a big red boat with a big red sail.

"My experience in past campaigns is it is really difficult to get an accurate judge on performance from reconnaissance.

"They have guys following us, and we have guys following them. You can see the sails, photograph the sails and foils when the boat is going in and out.

"But knowing exactly what the wind angle is, wind speed, boat speed … it is very, very difficult, almost impossible.

"So you've got to take it with a grain of salt. In past campaigns I've been told 100 per cent this is happening, and when you go out there it is the complete opposite.

"But we have had the Christmas Cup and official practice days so we do have a read off them."

Spithill said advantages were shared, with the defenders limited to practice while Luna Rossa raced in the Prada Cup.

"They would have more data on us just from watching the broadcasts … you can hear what is happening on board so they have that up their sleeve," Spithill said.

"But we've had real racing, that's the difference. It's a double-edged sword.

"We've had sudden death, real pressure … they've had to train on their own."

There were changes the teams could make to things such as sails and software, but the big hardware items were locked in. Unlike past campaigns, appendages such as rudders and foils could not be changed. The teams were concentrating heavily on their boat handling.

And when asked about reported comments from co-helmsman Francesco Bruni, to the effect that Burling lacked match racing experience, Spithill lavished praise on a range of TNZ members and said New Zealand journalists could miss some Italian language nuances.

"Burling is the best in the world, without a doubt," he said.

"I've got a huge amount of respect for them … they are good mates of mine, an incredible team.

"We are going up against the world's best but that's what we live for. If it was easy it wouldn't be worth doing.

"Both teams are fully set to go - it really can't come soon enough."

Heart rates

Spithill told Hosking that the twin-helmsman system used by Luna Rossa probably helped keep his heart rate down.

Spithill's monitor shows his BPM reading stays in the 60 and low 70s.

"This is the first time where I'm sitting down the entire time - most of the boats I've sailed in the past involved me swapping sides or jumping around," he said.

"The only guy on our boat who swaps sides is the mainsail trimmer Pietro Sibello. Francesco and I lock in for the entire race - we don't move.

"Genetically my dad has a pretty low heart rate as well, but I take my training pretty seriously and have taken another step in terms of diet. In the past I neglected that.

"I do a lot of physical training and I believe I make better decisions when my body is in good physical shape."

Spithill said he worked hard on remaining calm under pressure.

"In sport, life, business … the more stressed and emotionally wound up you are - it doesn't help you make good decisions," he said.

"It is something I've seen with mates in the military.

"I don't leave too many stones unturned. With a lot of the technology today there is always some way of getting better and learning. That's what makes it such an addiction."

Spithill said that after a decade with Oracle USA, he had been taken out of his comfort zone with the Italian team.

"I was in an Anglo Saxon culture - here I'm the only non-Italian, living in Sardinia for a few years," he said.

Heading into the Cup racing?

• Give yourself plenty of time and think about catching a ferry, train or bus to watch the Cup.

• Make sure your AT HOP card is in your pocket. It's the best way to ride.

• Don't forget to scan QR codes with the NZ COVID Tracer app when on public transport and entering the America's Cup Village.

• For more ways to enjoy race day, visit at.govt.nz/americascup