Kimi Raikkonen put Alfa Romeo on top of F1's second day of testing as 2020's expected frontrunners took a back seat on the timesheet.
But Mercedes, Day One's pacesetters, still made the biggest headlines of Thursday by debuting an innovative steering wheel concept which proved the talk of the paddock.
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- The fastest laps and mileage of Testing so far
Racing Point's Sergio Perez had led the timesheet for most of the day but he was usurped late on by Raikkonen, who completed some short bursts on Pirelli's fastest C5 tyre.
The veteran Finn's lap of 1:17.091 is the second quickest of the week so far behind Mercedes' Lewis Hamilton. Raikkonen stopped on track late on to bring up 2020's first red flag.
Hamilton and Valtteri Bottas again shared running at Mercedes, with the world champion clocking a mammoth 106 laps in the morning alone before his team-mate took over the W11 in the afternoon.
Bottas' session ended after 77 laps when an electrical glitch cost the world champions the closing stages of the day.
Daniel Ricciardo was third for Renault despite a few delays, ahead of Red Bull's Alex Albon, AlphaTauri's Pierre Gasly and Ferrari's Sebastian Vettel, who returned to action after feeling unwell on Day One.
Charles Leclerc had continued in the SF1000 during the morning before Vettel took over after lunch, with the four-time champion posting their quickest time so far of 1:18.154.
"It's not about the times for Ferrari, they want to run through all the set-up changes on the new car as has a wider set-up window to play with," said Sky F1's Ted Kravitz.
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With 25 per cent of winter testing complete already, Mercedes lead F1 2020's early lap count - the W11 has completed 356 laps, 54 more than next-best Red Bull - and have won the early prizes for design innovation.
The emergence of what they are calling DAS - Dual Axis Steering - appears to allow their drivers to 'toe-in' their front wheels down the straights by moving the steering wheel towards them in the cockpit.
"DAS is the big technical innovation of the week along with their rear suspension," suggested Kravitz.
But while their RB16 has made fewer early headlines, Red Bull have been satisfied with their early running as they prepare for what they hope is an all-out title challenge to Mercedes for the first time in the hybrid era.
"It has been positive for us so far. The car is behaving as predicted," team boss Christian Horner told Sky F1. "We're happy with everything we have achieved so far. This week is focused very much on getting mileage on the board and understanding."
Racing Point's start to the winter - third on the Day One timesheet and second on Day Two - comes amid focus on the similarities of their new RP20 to last year's title-winning Mercedes W10.
Meanwhile, Williams again completed over 100 laps to continue their much-needed positive start to 2020 - with George Russell finishing seventh - while Lando Norris was 10th for McLaren after 137 laps.
Haas' Romain Grosjean completed more laps than any other driver on Thursday, but a spin and subsequent contact with the Turn Three barriers cost him the day's final 40 minutes.
Watch every day of Winter Testing live on Sky Sports F1 and the Sky Sports App. The sessions run from 8am-12pm and 1pm-5pm, followed by The Story So Far featuring driver interviews and the verdict on the day.