In June, with preparations well underway, Luna Rossa Prada Pirelli team principal Patrizio Bertelli slammed the design of the AC75 monohull.
Speaking to Italian publication La Stampa, Bertelli said he wanted the 2021 edition to be raced on monohulls but the Team New Zealand design was "too difficult".
"I had suggested to the Kiwis to choose a less extreme boat than this one," he told La Stampa.
"A sort of modern VOR60 [the boat of the former Volvo Ocean Race] on which to develop two rudders with foils.
"The electronic part is especially complicated. We have been working on it for two years."
Meanwhile, Team NZ boss Grant Dalton said the monohull could turn upside down but was unlikely to do a dramatic pitch-pole like one of New Zealand's catamarans did in 2017.
Team New Zealand chief executive Grant Dalton with the America's Cup. Photo / Mark Mitchell
Speaking to the Herald from Italy last month, Dalton explained the boats were designed to be self-righting, depending on wind conditions.
"I don't think you'll see a face plant like we did in Bermuda because monohulls don't do that," he said.
"But you're more likely to see, and it's quite possible, that you'd see a boat, if it's manoeuvred incorrectly, roll over."
In a recent blow to the 36th edition of the Cup, Dutch Sail announced it had withdrawn from the race due to financial constraints.
The group made the announcement on July 1, the second withdrawal of a challenger in the past two months after a similar decision by Malta Altus.
Only Luna Rossa, Ineos, American Magic, and Stars and Stripes remain.
