Nico Rosberg set the fastest time of the morning session of the final test in Barcelona, with Mercedes running the soft tyre for the first time.
Mercedes looked in ominous form throughout the first test as it completed huge mileage while only ever running on the medium tyre which is the most stable compound for the conditions. Tuesday saw the Mercedes run the soft tyre for the first time and Rosberg duly set the fastest time of testing so far with a 1:23.022 at the start of a three-lap run.
Only Vettel has posted a quicker time so far during testing, with his lap of 1:22.810 coming on the ultrasoft tyre on day two last week. Tuesday morning saw Ferrari again quick. with Kimi Raikkonen second fastest on the medium tyre. Raikkonen's time of 1:24.836 saw him over 1.8s slower than Rosberg but came on a longer run than the Mercedes.
Fernando Alonso ensured McLaren bounced back from its troubles on the final day of last week by posting the third fastest time. Also running the soft tyre, Alonso was 2.2s slower than Rosberg but the huge gulf in terms of mileage between the teams means they are likely to be running very different programmes.
However, McLaren's morning was not without incident as Alonso stopped in the closing moments of the session at the pit lane exit, meaning the session ended under a red flag.
Williams was another team to set its best time on the medium tyre with Valtteri Bottas just 0.003s slower than Alonso's best on the softs, improving in the final hour before lunch on one of his 58 laps.
Max Verstappen was fifth fastest in the STR11, with Toro Rosso having launched its race livery on Tuesday morning ahead of the start of running. The Dutchman was just 0.104s slower than Alonso in third as part of a relatively close bunch behind Rosberg.
Sixth was Nico Hulkenberg in the Force India, just ahead of Daniil Kvyat as Red Bull had a quiet morning. Kvyat managed just 22 laps, as his session ended with the car smoking heavily in the pit lane.
Esteban Gutierrez fared little better in terms of mileage, with Haas last out of the garage at the start of the day and completing just one lap more than Red Bull. Haas still ended the morning session a quarter of a second clear of Felipe Nasr in the new Sauber C35, while Kevin Magnussen was slowest of those setting a time but managed 54 laps in the Renault.
Rio Haryanto endured a frustrating morning for Manor as an oil leak confined him to the pits for almost the whole session. Only one installation lap was possible before the team discovered the problem, and having rectified it just before lunch Haryanto had to immediately pit due to the red flag for Alonso's stoppage.
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