George Russell and Lewis Hamilton made it a Mercedes one-two ahead of title-chasing Max Verstappen in a wet-dry second practice on Friday for the Japanese Grand Prix.
Runaway Red Bull leader Verstappen can clinch his second straight world title on Sunday if he wins the race with the fastest lap, no matter what his rivals do.
But he was beaten to the quickest time in the second practice session by the Mercedes pair, with Russell clocking a fastest lap of 1min 41.935sec. Seven-time world champion Hamilton followed his fellow Briton 0.235sec behind, with Verstappen coming in third, a sizeable 0.851sec behind Russell.
A rainy start to the session at Suzuka meant the drivers began on wet tyres but switched to intermediates once the conditions improved.
That did not satisfy Verstappen though, with the flying Dutchman telling his team "all tyres are s---, no grip", over the radio.
Dry conditions are expected for Saturday's qualifying but some rain is forecast for Sunday.
"It's probably not going to be that representative for this weekend but definitely good learning for the future," Russell said of the conditions.
"Nevertheless, it's always nice to end the day top of the timesheets."
Ferrari's Charles Leclerc, Verstappen's nearest rival in the championship standings, finished 2.774sec behind Russell in 11th.