Oscar Piastri raised the prospect of a first non-Mercedes victory of the season after he finished fastest in the second practice session for Sunday's Japanese Grand Prix.
The McLaren driver edged out Kimi Antonelli by 0.092 seconds in Suzuka with George Russell third.
Lando Norris missed the first half of the one-hour session with a hydraulics leak and was fourth, half-a-second down on Piastri in the other McLaren.
Charles Leclerc finished fifth, a distant seven tenths behind Piastri, and one place ahead of Ferrari team-mate Lewis Hamilton. The seven-time world champion was 0.847 secs off Piastri's pace.
Piastri’s pace-setting effort capped an encouraging day for McLaren after both their cars failed to start in China.
Reliability concerns at McLaren linger, however, with Norris spending large parts of both sessions with his car being worked on in the garage.
Ferrari, the closest challengers to Mercedes in the opening two rounds, had Leclerc and Hamilton fifth and sixth in both sessions.
Red Bull's four-times world champion Max Verstappen was seventh fastest in the opening session and 10th in the second.
Audi's Nico Hulkenberg posted the seventh-quickest time in the second session ahead of Williams driver Alex Albon and the Haas of Oliver Bearman.
Fernando Alonso, who handed his Aston Martin over to the team’s third driver Jak Crawford for the opening session, was only 19th fastest at what is a home event for the team’s power unit partner Honda.
Hamilton landed the first Ferrari podium of his career in Shanghai but he appeared down on belief in practice.
“I am very slow because I have no confidence in the car,” he said in the closing moments of the session.
After his strong showing in China, British driver Ollie Bearman, currently fifth in the standings, took ninth spot.
Earlier, Formula One’s governing body announced it had changed energy management rules for Japanese GP qualifying to allow drivers to push harder.
The maximum energy teams will be allowed to draw from their hybrid power units during Saturday’s session will be reduced, the FIA said in a statement.
The change, agreed following unanimous support of the sport's power unit manufacturers, will “ensure that the intended balance between energy deployment and driver performance is maintained,” the statement said.
Formula One has introduced sweeping new rules this year, with the hybrid power units in the cars now split near 50-50 between electric and combustion power.
The new rules have resulted in wheel-to-wheel action in the first two races.
Critics, though, have said it has taken some of the thrill away from the usually flat-out qualifying laps by turning them into a test of battery management rather than driver skill and courage.
