Lewis Hamilton said Mercedes had their “best session of the year” in Friday’s practice at the Japanese Grand Prix.
The seven-time champion was fifth quickest, with team-mate George Russell fourth, both just under 0.5 seconds behind Max Verstappen of Red Bull.
The times were set in the first session, while the second was rendered irrelevant by wet conditions.
Hamilton, said: “It was a really good session, the best the car has felt this year.”
Mercedes expected to struggle at Suzuka because its demanding, high-speed layout layout should expose the car’s limitations in high-speed corners.
Mercedes have been struggling to understand why the car produces less downforce on track than their simulations suggest it should.
Hamilton said: “It felt really positive. I was excited, because this is a circuit every driver loves to drive and the last couple of years we’ve had a really difficult car and balance to drive here.
“And given the difficult last few races we’ve had, great work has been done and we seem to have hit the ground in a sweeter spot so I haven’t really made any changes.”
Russell, who was 0.013secs quicker than Hamilton, said the car’s performance was “a pleasant surprise”.
Verstappen led Red Bull team-mate Sergio Perez by 0.181 seconds, with Ferrari’s Carlos Sainz, winner of the last race in Australia, 0.213secs off the pace in third.
Behind the Mercedes were the the second Ferrari of Charles Leclerc and Aston Martin’s Fernando Alonso.
Both Red Bull and Aston martin have significant aerodynamic upgrades for this race, the fourth of the season, centring on modifications to the floors of their cars.
But Verstappen said he expected the field to be closer than it was at last year’s Japanese Grand Prix, when he took one of his most dominant victories in a season in which he won 19 of the 22 races.
The Dutchman, who was on pole by nearly 0.6secs last year, said: “It was a good start for us. The balance wasn’t too far out but it does look like everyone is a bit closer compared to last year. I don’t expect gaps to be like last year.”