First practice at the Las Vegas Grand Prix was called off after just nine minutes of running because of a problem with a manhole cover.
Ferrari’s Carlos Sainz stopped out on track on the Strip and the session was stopped shortly afterwards. Ferrari said they did not initially know what had happened.
The chassis of Esteban Ocon’s Alpine was damaged by running over a drain cover.
Governing body the FIA said there would be an indefinite delay while all manhole covers around the track were checked.
A spokesperson said: “Following inspection, it was the concrete frame around a manhole cover that has failed.
“We now need to check all of the other manhole covers, which will take some time.
“We will be discussing with the local circuit engineering team about the length of time it will take to resolve and will update with any resultant changes to the schedule.
Alpine said they were changing the chassis of Ocon’s car because of the damage.
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 George Russell’s Williams hit a drain cover and was badly damaged.
Second practice was due to start at 00:00 local time in Las Vegas (08:00 UK).
At the time the session was stopped, drivers were just beginning to familiarise themselves with the track.
Charles Leclerc’s Ferrari was faster by 2.5 seconds from the Haas drivers Nico Hulkenberg and Kevin Magnussen.
