Sebastian Vettel set the pace as Ferrari dominated final practice at the Canadian Grand Prix.
Vettel was ahead of team-mate Kimi Raikkonen by 0.292 seconds as Mercedes appeared to struggle for grip.
Lewis Hamilton was 0.354secs behind title rival Vettel in third place, while his team-mate Valtteri Bottas survived a wild moment at Turn Four.
The Red Bull of Max Verstappen split the Mercedes with fourth fastest time as the track improved.
The Dutchman’s position – just 0.393secs off Vettel’s best – was probably flattered by the timing of his run. He ran at the end of the session when the Ferrari and Mercedes drivers did their qualifying simulation runs about 15 minutes before the end of the session.
Under big, blue Quebec skies, there were fewer spins than during Friday practice but a couple of very near-misses with the walls.
Bottas came the closest, his Mercedes flicking from side to side as he pushed the limits through the tricky Turn Three/Four chicane, where the track cambers change mid-corner and the circuit drops away downhill on exit.
Jolyon Palmer also had a moment there, the Renault missing the wall by millimetres as he suffered a flick of oversteer on the exit, as did Sauber’s Marcus Ericsson, who took to the grass after misjudging the entry.
Palmer, whose seat is under threat, continued to struggle, the Englishman ending the session 15th – nine places and 0.6secs behind team-mate Nico Hulkenberg, who was an impressive sixth fastest.
Williams’ Felipe Massa was seventh, his team-mate Lance Stroll struggling so far on his debut at his home race with the 18th fastest time, nearly a second behind the Brazilian.
The second Red Bull of Daniel Ricciardo was eighth, but at least managing a full session after missing most of second practice on Friday because of a major failure of his Renault engine.
Force India’s Esteban Ocon took ninth ahead of the Toro Rossos of Carlos Sainz and Daniil Kvyat, and the McLaren-Honda of Fernando Alonso.