Valtteri Bottas has stolen the headlines on an intriguing day of pre-season testing in Barcelona as the majority of F1 teams complete race simulations which gives a brighter picture on the 2016 challenger's full potential, but it was a horrific day for Haas who missed the day with a turbo charger problem.
With only Williams and Renault experimenting with tyre compounds beyond the yellow-band soft Pirellis, Bottas duly clinched top spot with a 1m 23.261s with a qualifying-style run on the super-softs. His time bumped Lewis Hamilton's morning topper into second with Kevin Magnussen's best time on the super-softs completing the top three.
As track conditions heated up in the afternoon, every team apart from Sauber and Manor ran some form of race simulations but it became another painful day for Esteban Gutierrez and Haas who effectively spent the whole day off track.
Having fallen to a fuel system issue midway through the first day of the second test, which meant Gutierrez could only complete 23 laps, the Mexican produced a total of one installation lap before a problem with the turbo charger ended his running before it truly began.
Sauber also suffered teething problems with its new C35, which had only made its track debut yesterday, as Marcus Ericsson was limited to just over a half-century of laps. Having been stuck in the pits for large period of the afternoon for system checks, Ericsson lost a wheel at turn four on his third lap of the session and spun into the gravel.
The Swedish driver and car were safely recovered under red flag conditions and subsequently missed the remainder of the day's track action.
With the majority of teams running race simulation work the Mercedes pace looked ominous with Nico Rosberg at the wheel, while Hamilton topped the morning session having made the best of the yellow-band soft tyres.
Ferrari might be concerned about Sebastian Vettel's lack of lap-by-lap pace in a race simulation compared to the Mercedes, albeit on different engine settings and fuel loads.
Conversely, Carlos Sainz's race pace impressed using the year-old Ferrari power units in the new-look Toro Rosso as he matched Vettel and Red Bull's Daniel Ricciardo.
McLaren-Honda looks to have resolved its reliability issues which plagued its opening test as Jenson Button comfortably topped a century of laps, ending the day fifth overall.
Force India produced another low-key but consistent day's running as Sergio Perez returned to the cockpit of the VJM09, as Pascal Wehrlein completed the overall top ten in the Manor.