Lewis Hamilton has described the Las Vegas Grand Prix track as "massively challenging" owing to the unique demands placed on the cars.
The high-speed street track demands low downforce, but this makes it tricky to generate tyre temperature through the heavy-braking zones and through the heart of the lap, which is further heightened by low air temperatures.
Action was further delayed after FP1 was abandoned following the Carlos Sainz drain strike, with the seven-time World Champion posting the ninth fastest time in the two-and-a-half hour delayed session.
It was run effectively behind closed doors after fans were ejected owing to stewards' shifts finishing at 01:30 local time - 60 minutes before the session finally got underway.
Hamilton ended 1.4s down on Charles Leclerc in P1, but was a more encouraging 0.6s down on P2 finisher Carlos Sainz on a track where the long 1.2-mile blast down the Strip would expose Mercedes' weakness of a lack of straight-line speed.
Owing to the nature of the track, minimum downforce and skinny wings are uniform across the field, with Hamilton believing the track to be "massively challenging" but conceded he did have "blast" in the W14.
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"It's massively challenging and even though we've got the long straights, there's not really a lot of places to overtake," Hamilton told Sky Sports F1 after the heavily-delayed and extended practice session.
"The grip is low and the tow is not huge, a bit like Monza where you are behind people with a small wing, there is not a lot of drag.
"It is going to be interesting, in qualifying, I think position is going to be really important and obviously the race is going to be key.
"But I had a blast, everyone is struggling with jet lag and all that stuff, and I feel great.
"I'm so glad that we did get to run again, and it is not great what happened but they did a great job to fix it.
"[The balance] is okay, it is not too bad. I think when we are all out on the Soft tyres, we're not too far off, and everyone is having graining and running out of tyres but everyone is in the same boat.
"We're on really low downforce so you're sliding a lot through a lot of the low-speed corners and also the high-speed corners quite a lot as you don't have a huge amount of load.
"You need the straight line speed, and then the [low] temperatures I'm sure are having a big effect."