Lando Norris and McLaren team-mate Oscar Piastri have won seven races each this season
McLaren's title contenders Lando Norris and Oscar Piastri struggled in first practice at the Las Vegas Grand Prix as Ferrari's Charles Leclerc set the pace.
Norris and Piastri ended the session on a dusty track in sixth and eighth places after a series of off-track moments.
Norris was 0.456 seconds slower than Leclerc, who headed Williams' Alex Albon by 0.166secs.
Red Bull's Yuki Tsunoda was third, ahead of team-mate Max Verstappen for the first time since they have been team-mates this year.
