Valtteri Bottas set the pace for Mercedes in final practice for the Chinese Grand Prix on Saturday ahead of qualifying for Formula One's 1000th world championship race.
The Finn, who leads the overall standings by one point from team mate Lewis Hamilton and ended Friday's practice sessions with the fastest time, set the timing screens alight with a lap of one minute 32.830 seconds.
Sebastian Vettel was second fastest, 0.392 seconds off the pace and ahead of Ferrari team mate Charles Leclerc.
Hamilton, a record five-time winner in China who struggled to get the car to his liking during Friday's running, was fourth 0.859 seconds off his team mate's pace.
The gaps could be exaggerated, however, with a mistake forcing Hamilton to abort his first attempt at a flying lap when his tyres would have been at their freshest.
Vettel's best effort was also compromised by an error.
The session was red-flagged with seven minutes left on the clock after a massive crash for Toro Rosso's Alex Albon.
The Thai driver, who escaped unhurt, lost control at the exit of the final corner and slammed into the barriers with the mangled car coming to rest across the start-finish straight in a shower of carbon fibre debris.
Nico Hulkenberg was fifth for Renault ahead of Kimi Raikkonen in the Alfa Romeo.
The Finn had a close call with team mate Antonio Giovinazzi with Raikkonen accusing the Italian of almost hitting him on purpose over the team-radio.
Max Verstappen was seventh for Red Bull, with the team appearing to have lost some speed after a promising showing in Friday's practice sessions.
Carlos Sainz was eighth for McLaren.
Despite his crash, Albon still clocked the ninth-fastest time but his participation in the qualifying session later in the afternoon depends on whether his mechanics can rebuild his car in time.
Team mate Russian Daniil Kvyat rounded out the top 10.