Sergio Perez emerged on top of the pile with the quickest time on the penultimate day of testing in Barcelona.
The Sauber driver set his benchmark time of 1min 22.094secs during a qualifying simulation shortly before lunch, before switching to race simulation work in the afternoon.
The appearance of rain as the afternoon wore on helped ensure that the Mexican remained top of the times, although he was barely 0.009secs clear of the McLaren of Jenson Button.
Button had started the day with a quiet morning, with just 17 laps completed before the lunchbreak. The Briton was also quiet during the afternoon as he completed only 44 laps in total – although he was one of the few drivers in the afternoon to set a quicker time as he jumped up to second place.
Daniel Ricciardo was a solid third as Toro Rosso continued to show encouraging pace while Felipe Massa was fourth for Ferrari – both drivers electing to head out on intermediate tyres when the rain fell during the afternoon.
Force India's Paul di Resta was fifth quickest ahead of Bruno Senna, who brought out the red flag during the afternoon when he stopped on track in the new Williams. Heikki Kovalainen was seventh for Caterham, with Mark Webber down in eighth having focused on short runs in the heavily revised Red Bull.
Nico Rosberg was ninth for Mercedes, albeit within a second of the quickest time, with Kimi Raikkonen propping up the rear for Lotus having struggled with a steering issue during the morning session.