Red Bull Racing has possibly unearthed the cause behind Sebastian Vettel's slightly off-colour form over the last two grands prix in Spain and Monaco - with a 'defect' in the young German's chassis meaning he will have to ditch 'Luscious Liz' and race a different monocoque from Istanbul.

Having set pole position for three of the opening four outings of the F1 2010 World Championship campaign, Vettel was forced to give best to team-mate Mark Webber in both Barcelona and Monte Carlo, on neither occasion being able to hold a candle to the Australian in terms of pure pace.

Whilst Webber triumphed back-to-back with commanding lights-to-flag performances, Vettel faded to an eventual third place as he found himself stymied by brake woes in the latter stages around the Circuit de Catalunya, whilst the 22-year-old had to stave off an inspired Robert Kubica in the unfancied Renault for the runner-up laurels in the Principality. Now, it seems, the Heppenheim native might in effect have been fighting with one hand tied behind his back.

"We have found a defect in Sebastian's chassis," Red Bull team principal Christian Horner told German publication Auto Bild Motorsport, adding that the problem had likely deteriorated as the Monaco Grand Prix wore on and was discovered back at the factory in Milton Keynes post-weekend. "For the next race in Turkey, he will have a new chassis."

The RBR pairing currently sit tied on points atop the drivers' title standings, but it is Webber who palpably has the most momentum as the season enters its middle stretch, and it is the New South Wales native who finished ahead in Istanbul twelve months ago. Horner, however, is confident Vettel will rapidly regain his full potential.

"Sebastian began the season in great shape, and I am sure he will bounce back at the next race," asserted the Englishman, a former racer himself. "In Barcelona and Monaco, Mark was simply stronger - he had more confidence and felt more comfortable in the car. In contrast, Sebastian complained several times about the balance."