Fernando Alonso today provided firm evidence of his rivals' pre-race suspicions that he is a contender for European Grand Prix victory on Sunday.
Alonso pushed McLaren duo Lewis Hamilton and Jenson Button close in the previous race in Canada, and but for becoming embroiled with a couple of backmarkers could have potentially claimed the win.
Around Valencia's 5.419km track that winds itself around the port area of the city, the Ferraris are sporting their version of the blown diffuser that has so far proven successful for Red Bull.
In simple terms, exhaust gases are directed through the diffuser, so speeding up the air flow, aiding grip, and ultimately performance.
Mercedes and Renault also have the device on their cars for the first time, and the question now is just how close those three teams can push Red Bull and McLaren.
In front of his home fans, Alonso posted the quickest lap of the day with a time of one minute 39.283secs, just 0.056secs ahead of Sebastian Vettel in his Red Bull, and quicker than last season's pole time set by McLaren's Lewis Hamilton.
Red Bull team principal Christian Horner does not feel this track suits his team's car, but Vettel and Webber made light work of that suggestion, with the latter third quickest, 0.144secs adrift.
As ever, practice is never a true yardstick of what will transpire in qualifying, but it offers an indicator, and at present all the major players are in contention.
Mercedes' Nico Rosberg, quickest in the morning session, was down in fourth in the afternoon, followed by championship leader Hamilton.
McLaren will not have their own version of the blown diffuser until the British Grand Prix at Silverstone in a fortnight, so they are playing a waiting, watching game.
Renault's Robert Kubica is another expected to fare well, and the Pole was sixth quickest for the day ahead of Ferrari's Felipe Massa.
The Brazilian, though, lost track time as he spun after just 30 minutes, leaving his car in the middle of the track and facing the wrong direction.
In failing to keep his engine running, and with the anti-stall not kicking in either, Massa had no choice but to clamber out of his stricken car that had to be hauled away by a crane, although he did return 30 minutes later.
Force India's Adrian Sutil, Jenson Button in his McLaren and the Williams of Rubens Barrichello, winner here a year ago when then with Brawn GP, completed the top 10, all within a second of Alonso.
Seven-times champion Michael Schumacher, taking to the track for the first time today after being previously being in retirement when the last two races have been run, was 1.004secs down in 11th.
Renault's Vitaly Petrov was another spinner, but unlike Massa was at least able to keep his engine going, finishing 13th behind the second Force India of Vitantonio Liuzzi.
Virgin Racing's Timo Glock was another casualty as his car ground to a halt with a technical issue and he also had to be craned away after 53 minutes.
Hispania Racing duo Bruno Senna and Karun Chandhok finished at the bottom of the standings, 4.8secs and 5.2secs adrift respectively.