Lando Norris believes the Formula One drivers' championship battle could shift in his favour after Red Bull were made to alter a controversial ride-height device found in their car.

On Thursday, it was confirmed that Red Bull had agreed a plan with the sport's governing body, the FIA, to remove a device that could potentially have been used to adjust the height of the car floor.

Alterations to cars when in restricted 'parc ferme' conditions between sessions on race weekends are prohibited.

Red Bull officials insist the device could not be used when the car is fully assembled, with the FIA saying there had been "no indication" of it being used to breach regulations.

However, Norris – who is 52 points behind Max Verstappen at the top of the drivers' championship standings – believes it could have given Red Bull a slight edge.

"It's one thing having it on your car, it's another thing how much you exploit it and use it, which we have no idea on," Norris said on Friday.

"If it has been helping them, if they have been utilising it in a way people think they have, maybe it will shift in our direction.

"But, when you talk about things like that, they won't have got several pole positions or wins because of that device.

"I don't think it will change anything in the scheme of things. Maybe at certain qualifying sessions, when it has been split by hundredths or thousandths, you might say, 'okay, maybe this has helped in this direction or that direction.'"

Verstappen and Norris were third and fourth, respectively, in the only practice session ahead of Sunday's United States Grand Prix, with Ferrari dominating.

Carlos Sainz set the pace, 0.021 seconds ahead of team-mate Charles Leclerc and 0.253 quicker than Verstappen.

Lewis Hamilton was fifth ahead of Mercedes team-mate George Russell despite a high-speed spin early in the session, with qualifying for Saturday's short sprint race taking place later on Friday.