Sebastian Vettel denied home hero Fernando Alonso a clean sweep of fastest times by edging the Spaniard to the tune of 0.017secs in the afternoon session at the Circuit de Catalunya.
Morning times, except for those of Heikki Kovalainen and Rodolfo Gonzalez, were rendered meaningless as the sun came out over Barcelona and allowed all eleven teams the chance to try their latest development, as well as Pirelli's prototype tyre, on a dry surface.
Although the order changed continuously in the early stages, it was world champion Vettel who emerged on top, and remained there to the end as teams switched to longer runs in preparation for Sunday's race. The German posted a benchmark of 1min 22.808secs, comfortably bettering Alonso's best of 1min 25.252secs, but could not shake the Ferrari driver's attentions as the pre-race favourites duked it out for top spot.
Mark Webber completed a strong afternoon for Red Bull by slotting into third place, also less than a tenth off his team-mate's time, while Kimi Raikkonen ensured that Lotus would also be bracketed with the expected frontrunners. The Finn headed a tight second group, including Felipe Massa and Mercedes twins Lewis Hamilton and Nico Rosberg, covered by a matter of tenths, with eighth-placed Adrian Sutil fully half a second further back.
The German helped sandwich FP1 surprise Jean-Eric Vergne between the two Force India cars, but fared better than team-mate Paul di Resta who, despite claiming tenth overall, failed to finish the session after suffering a delamination on the left rear while running Pirelli's medium compound tyre. The 'failure' mirrored those suffered by Hamilton and Massa in Bahrain, and immediately attracted the attention of the Pirelli technicians….
Outside the top ten, Daniel Ricciardo underlined STR's positive day by pipping both McLarens to eleventh, with Jenson Button and Sergio Perez next up for the Woking team, which brought probably the biggest raft of changes to its car as the European season got underway.
The silver cars featured updates to its sidepods and the wings at the front of them, as well as changes to both front and rear wings, the former finally being bolted to Perez's car in the closing moments of the second session.
Down at Ferrari, there were also new sidepods and an updated front wing, whilst Red Bull, despite Vettel's claims that there would not be much difference to the RB9, was clearly running revisions to its rear wing. Lotus, meanwhile, brought new sidepod winglets, rear wing changes and a revised diffuser to its E21, while Caterham introduced its 'definitive' 2013 machine – with a noticeably different look – after running an interim machine at the four 'flyaway' rounds.
The changes, as well as Giedo van der Garde's acknowledged history at the Circuit de Catalunya, allowed the Dutchman to top 'division three' ahead of Marussia's Jules Bianchi, Caterham team-mate Charles Pic and the other MR02 of Max Chilton, which suffered a couple of niggling problems early on, after the Briton had reclaimed his seat from reserve Gonzalez.
A little further up, Sauber continued to struggle for pace, with Nico Hulkenberg claiming that he felt slow down the straights. Despite upgrades to the front of his car, the German trailed Valtteri Bottas' Williams as the two teams appeared to lose ground to Toro Rosso in the battle of the midfield.