MOTOR SPORT EUROPEAN GRAND PRIX:IT'S A familiar Formula One story: team unveils car in pre-season testing, shocks rivals with great technical leap forward and dominates from the off.

There is always, though, a postscript, which relates how the dominance fades as an engineering war brews. By mid-season any advantage displayed by one team is invariably dulled.

This season has largely been a tale of two devices – the F-duct, which boosts pace in a straight line, which has allowed McLaren to take four wins, and the so-called “blown diffuser”, a deployment of the exhausts which has made Red Bull Racing vastly quicker through the corners than anyone else. So far it’s given them seven pole positions from eight races and three wins.

Yesterday in free practice for the European Grand Prix, though, the blown diffuser gambit was blown open as several teams brought their versions of the system to Valencia.

Red Bull’s Sebastian Vettel and Mark Webber, both running their implementation of the F-duct, were still in the mix, ending the day second and third respectively, but it was Fernando Alonso who topped the time sheet.

As for the McLarens, neither Lewis Hamilton, winner at the two most recent venues where their F-duct has given them an edge, nor Jenson Button ran with a diffuser solution and both finished the day further off the pace than in Canada or Turkey, with Hamilton fifth and his team-mate ninth.

“It was always going to be interesting to see how quickly the blown-diffuser cars could get up to speed – and they looked very competitive,” said Hamilton, whose team will not introduce its version of the diffuser until the British Grand Prix in a fortnight.

Alonso, having seen good Friday pace decimated by Vettel and Webber in qualifying numerous times this season, reserved judgment on how much of an advantage the system will give Ferrari when battle properly commences this afternoon.

“It’s difficult to know exactly what was the improvement, so we’ll wait for tomorrow to see if we are really more competitive,” he said.

“Sometimes we’ve been very quick on Friday. We were P1 last year here and then P8 on Saturday, so the job we have to do is in qualifying and on Sunday.”

Alonso may have grounds for scepticism. The engineering march may have narrowed the gap but Red Bull Racing boss Christian Horner remains unfazed by rival advances.

“It is difficult to cherry pick items if they are not designed into the architecture of the car. The exhausts are not the fundamental reason why our car is fast.”