Williams’ Carlos Sainz was fifth, whereas Racing Bulls’ Isack Hadjar took seventh along with his closing lap of the session. Mercedes’ George Russell was ninth, forward of team-mate Kimi Antonelli and Ferrari’s Lewis Hamilton.
Norris took to the escape highway at Flip 14 on the finish of Las Vegas’ well-known Strip twice on consecutive laps as he fought to search out tempo in his McLaren.
He additionally hit the wall early within the session, though he escaped with out damaging the automotive.
Piastri, 24 factors behind the Briton on the head of the championship, had his off-track second at Turns Eight and 9 across the Sphere.
The Australian was 0.192secs slower than Norris, persevering with the efficiency development between the 2 in most up-to-date races.
Norris has gained 58 factors on Piastri up to now six races, to take management of the season and put himself inside sniffing distance of the championship.
Leclerc was fast all session, however Hamilton ended up 0.759secs behind his team-mate.
The session is unlikely to be consultant of the remainder of the weekend because the monitor is so soiled and can enhance because the periods tick by.
Second observe is at 04:00 GMT.
