Daniel Ricciardo posted a new unofficial lap record around the current layout of the Circuit de Barcelona-Catalunya to lead both Mercedes drivers on the second day of the second test.
The Red Bull driver completed a full Grand Prix weekend simulation, posting a 1:18.047s on the Hypersoft tyre in his mock qualifying run late in the morning, surpassing the previous mark set by Felipe Massa in testing in 2008.
In the afternoon, Ricciardo then became the first of two drivers to complete a full race distance, running a 66-lap stint complete with pit-stops as part of a massive total of 165 on the day.
Lewis Hamilton and Valtteri Bottas both would set their best time on the Ultrasoft compound rubber, one step harder than the leading Australian, but the world champion would be .353s down in second with his teammate a further tenth-and-a-half back.
The other main story of Wednesday was the ongoing woes at McLaren as, after a strong start with 46 laps on the board, Fernando Alonso would come to a halt at Turn 7 two hours in, causing a red flag.
An oil leak was given as the cause of the failure and the Spaniard would not be seen again until the final 13 minutes of running, he would, however, set the fifth best time.
Elsewhere, Ferrari ran a split program with Kimi Raikkonen feeling unwell in the morning. Sebastian Vettel would take over for the first four hours, setting the fourth best time before handing over the Finn in the afternoon.
Using the Soft compound the Scuderia's times were some way off their rivals with Vettel one-and-a-half seconds slower than pacesetter Ricciardo.
Brendon Hartley would have a minor problem in the afternoon, otherwise it was another good day for Toro Rosso-Honda as the New Zealander completed 118 laps, setting the fifth best time.
Renault would get through a monster program of their own with their two drivers as, firstly, Carlos Sainz did 88 laps, setting the sixth best time on Medium tyres before Nico Hulkenberg would do a full race simulation in the afternoon as part his overall tally of 102.
The result would be 190 laps for the Enstone team, the most of any team on the day and in direct contrast to the problems their customers, Red Bull and particularly McLaren, have had so far.
Romain Grosjean continued Haas' steady pre-season with a solid 75 laps and the seventh best time, just 0.005s ahead of Raikkonen's Ferrari.
Williams had a productive day with Lance Stroll and Sergey Sirotkin combining for 139 laps but with the Canadian in 10th and the Russian 14th (bottom of the times), the pace still isn't inspiring.
The same can be said of Force India with Esteban Ocon only 12th, though 130 laps was a good return for the Frenchman albeit 30 less than Sauber driver Charles Leclerc as the Monegasque managed 160 tours but only the 13th best time.
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