Jenson Button set the fastest time of Tuesday morning at the post-race test in Barcelona, edging out Sebastian Vettel by 0.010s.
Button was the only driver to use the supersoft tyre during the opening four hours of running in Spain, post a 1:23.753 which was just 0.2s quicker than Fernando Alonso's qualifying time on Saturday. Honda confirmed there are only some ancillary updates being tested this week, with no major new components or upgrades.
Vettel's time came on the soft tyre in the final hour of running before the lunch break, with Ferrari carrying out some short runs in an attempt to understand its qualifying struggles from Saturday. Interestingly, Vettel was able to set the fastest final sector of anyone during the session, with the Ferrari having been weakest in sector three all weekend.
Nico Rosberg was third fastest as he returned to the Mercedes following the collision with team-mate Lewis Hamilton on Sunday. Mercedes carried out its running on the medium compound, with Rosberg managing 54 laps but setting a time 1.3s off Button's pace.
Williams was fourth quickest and caused a stir at the start of the session with Alex Lynn emerging from the garage with a radical rear wing design. The set-up included an extra wing and winglets above the usual installation, with additions to the front wing as well. Williams confirmed to F1i the approach is "to gain a better understanding of the car aero balance over a lap", though the items will not be allowed to be raced.
Daniel Ricciardo completed 31 laps - the lowest of any driver - after a long spell in the garage during the middle of the session. Red Bull is running its race drivers this week in order to give Spanish Grand Prix winner Max Verstappen more time to acclimatise to the car following his switch from Toro Rosso.
Renault is testing its B-spec power unit this week, with Esteban Ocon completing 47 laps with the new engine. The upgrade was notably louder out on track, and ran reliably throughout the session.
LIVE: Barcelona post-race - Day 1
Spanish Grand Prix - Quotes of the weekend
DRIVER RATINGS: Spanish Grand Prix
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