Lewis Hamilton has described the Miami International Autodrome's tight chicane as like "being in a B&Q car park" when he was starting out in go-karts.
The narrow section at the end of the middle sector through turns 13 and 14 ultimately accounted for Ferrari's Carlos Sainz in the second practice session as the Spaniard careered off into a barrier.
Offering his first impression of the circuit, the seven-time champion initially described it as "bumpy".
Mercedes driver Hamilton added: "It's kind of crazy. In this day and age, they should be able to make a flat road relatively easy but there are fricking big. big bumps in so many places where the track joins up somewhere else.
"I don't know if they'll be able to grind that overnight and improve it but otherwise it's quite nice to drive except for the chicane, that might be...I don't want to put that quote out there. I'll hold onto that.
"But it's so tight. It reminds of being in a B&Q car park when I was six, seven years old in a go-kart going in between cars.
"It's a corner that maybe in the future they can remove and it will improve the track."
Miami heat reminds Hamilton of Malaysia
Another concern for Hamilton was the heat and high humidity, with temperatures at 30 degrees Celsius and set to hit 33 for Sunday's race.
"It's very hot out there," added Hamilton. "I think today I've already lost a couple of kilos, another two tomorrow, and then the race is going to be right up there.
"It reminds of driving in Malaysia. It's not far off that. KL is still number one in terms of the heat, then Singapore and now it's here."
Hamilton eventually finished fourth quickest, with team-mate George Russell fastest as Mercedes' upgrades to its W13 that included new front- and rear-wings appeared to improve pace and stability, with little sign of the previously aggressive porpoising.
Hamilton, though, disagreed as he said: "It [the car] feels similar to me.
"We seem to be quicker and it was explained that we definitely have improved in some way, I'm not sure where that is.
"We still have the bouncing so we haven't cured it but bit by bit we are improving the car.
"There are definitely positive elements to take from today. I'm still struggling with the car. George looked great out there but we're trying a lot of different things. We'll converge and hopefully improve."