The first day of the much-vaunted Las Vegas Grand Prix descended into chaos as practice was hit by problems with the new street track.
The first session was called off after just nine minutes of running when Carlos Sainz's Ferrari hit a loose manhole cover, badly damaging his car.
Ferrari team principal Frederic Vasseur said the situation was "unacceptable".
The second session started two and a half hours late in front of almost empty stands after fan areas closed.
F1 said the decision, made at 01:30 local time, was caused by "logistical considerations for our fans and staff".
Esteban Ocon's Alpine was also damaged - like Sainz's Ferrari, losing a chassis - after he hit the same manhole as Sainz on his return to the pits after the red flag.
When track running finally finished, Charles Leclerc led Sainz by 0.517 seconds in a Ferrari one-two ahead of Aston Martin's Fernando Alonso and Red Bull's Sergio Perez.
World champion Max Verstappen was sixth fastest, Lewis Hamilton ninth and George Russell 12th for Mercedes and Lando Norris in 11th for McLaren.
Tempers fray under pressure
Amid the confusion between the cancelled first session and restarted second one, Mercedes team principal Toto Wolff swore at a journalist in a news conference when he suggested the situation was bad for F1's image at such a high-profile event.
"It's completely ridiculous," Wolff said. "How can you even dare trying to talk bad about an event that sets the new standards to everything?
"And then you're speaking about a [expletive deleted] drain cover that's been undone. That has happened before. That's nothing.
"Give credit to the people that have set up this grand prix, that have made this sport much bigger than it ever was.
"[F1's owners] Liberty has done an awesome job and just because in FP1 a drain cover has become undone we shouldn't be moaning.
"The car is broken, that's really a shame. For Carlos it could have been dangerous, so between the FIA and the track everybody needs to analyse how we can make sure that this is not happening again.
"But talking here about a black eye for the sport on a Thursday evening? Nobody watches that in European time anyway. Come on."
F1, which unusually is acting as the promoter for this grand prix, has spent more than £500m on preparations for the race. This includes a buying plot of land in Las Vegas, on which it has built the largest pit building on the F1 calendar and prepared the track.
The pit building will become a permanent presence for F1 in the Nevada city.
Hosting a grand prix in Las Vegas is the culmination of 40 years of on-and-off effort and has succeeded because of buy-in from the casinos, who expect to make millions of dollars and see the race as part of Las Vegas' bid to become a global centre for sport.
However, although F1 built the track, the responsibility to check it for safety was that of governing body the FIA, which did so before practice started.
What happened with the manhole cover?
Sainz hit a manhole cover on the headline part of the track - the long straight that runs along the famous Strip, home of all the famous casino hotels in Las Vegas.
To add insult to injury, Sainz has also received a 10-place grid penalty because the new battery needed to replace the one damaged in his crash was outside his permitted allocation.
Ferrari pleaded for mitigation on the basis that it was unusual circumstances but the stewards reacted their appeal.
Vasseur said the damage to the car would "cost a fortune".
The Frenchman took a different view from Wolff on the problems that hit the organisation of the race.
"I am very happy with what [F1 owners] Liberty [Media] did around the race but we have to separate the show and the sporting side," Vasseur said.
"The opening ceremony [on Wednesday] was something mega in F1 but it is not because you are doing this that you don't have to do the job on the sporting side. You can do the show and do a good job on the sporting side."
McLaren Racing chief executive officer Zak Brown said: "I don't think it was because corners were cut. They have spared no expense on the event. We just have to work out what happened and fix it. I think they just got it wrong."
Alpine were also forced to replace the chassis on Ocon's car following his incident. Like Sainz's, it was repaired in time to take part in second practice.
The team received no warning from race control about debris or problems on track before Ocon hit the manhole.
Alfa Romeo's Zhou Guanyu had a narrow escape. The Chinese was the first driver along after Sainz's incident and had to take avoiding action to miss the detached drain cover.
It is not the first time a drain cover has caused problems on an F1 track.
At the 2019 Azerbaijan Grand Prix, first practice was cancelled when Russell's Williams hit a drain cover and was badly damaged.
Similar incidents have also happened in Monaco, another street race.
What did the drivers say?
The session finished at 04:00 local time and many drivers said they were struggling with adjusting to the timings of the race.
Russell said he had had a total of four naps during the day, adding: "I don't know what time it is but I'm definitely looking forward to getting some sleep."
He added: "It was good to finally get going after quite a long day. A very fast circuit, highest top speeds of the year probably. I think it is going to be an interesting race weekend.
Hamilton said the circuit was "incredibly fast and a lot of fun" and "massively challenging".
"Even though they have the long straights, there are not a lot of places to overtake because the grip is so low. And the tow is not huge... a bit like Monza when you're behind people because you have the small wing and there is not a lot of grip."
Verstappen disagreed, saying he "had had better tracks in my life - I already said that yesterday; there is nothing new I discovered".
