George Russell was fastest in Saturday's free practice in a strong headwind as champions Mercedes bounced back from a disastrous opening day at the Emilia Romagna Grand Prix.
Lewis Hamilton was fourth quickest in the other Mercedes as the team made the best of warmer dry conditions at the Autodromo Enzo e Dino Ferrari. The seven-time champion had said Mercedes 'underperformed as a team' on the opening day.
Sergio Perez was second for Red Bull ahead of championship leader Charles Leclerc's Ferrari. Fernando Alonso took fifth for Alpine and Carlos Sainz sixth in the second Ferrari ahead of world champion Max Verstappen in the second Red Bull.
The result was an unexpected turnaround for the 'silver arrows' after Friday's failure to qualify either car for the top-ten shootout for the first time in 10 years since the 2012 Japanese Grand Prix.
But it may not signal an upturn in race competitiveness in the 100-kilometre sprint race later on Saturday or Sunday's Grand Prix.
After Friday's deluge, Saturday's practice session began in warm sunshine and dry conditions with a track temperature of 31 degrees. The air temperature was 19 and rising and the circuit filled with animated 'tifosi' packing the stands and hillsides.
Hamilton, on medium tyres, was out in the early bunch of runners and was soon top of the timings in one minute 21.809 seconds, a marker rapidly eclipsed as the Red Bulls took control on soft tyres.
McLaren's pair, Lando Norris and Daniel Ricciardo, did not appear. The team said Ricciardo had "an issue" on his car. Valtteri Bottas's Alfa Romeo was also up on the garage jacks.
Leclerc came out, to the joy of Ferrari fans, but was apparently running with a heavy fuel load as he concentrated on preparation for the sprint race. Yuki Tsunoda, the only driver on hard tyres, was clearly more focussed on Sunday's Grand Prix.
By mid-session, Russell had gone quickest for Mercedes ahead of Perez and Hamilton, indicating a major shift in the team's fortunes after Friday's travails in the rain. All three were in the 1:19's.
But in 'sprint weekend' format, the session was not as representative of pure speed as usual for a Saturday ahead of a traditional qualifying.
Leclerc and Sainz were 10th and ninth and 'resting' back in Ferrari's garage before the Monegasque returned to go second on the softs with 15 minutes to go.
Sainz followed into sixth before Perez went second, both on mediums –- clear proof that the warmer weather enabled much better tyre performance, notably for Mercedes whose cars ran with a raised ride height on Saturday.