As he comes under mounting pressure to prove himself worthy of his place in Formula 1, S?bastien Bourdais has defended his rookie campaign in the top flight - insisting that 'it's not that I'm getting my a*se kicked every fortnight'.

The Frenchman arrived in the uppermost echelon this year as the reigning and record-breaking four-time Champ Car Champion across the Pond, but his points-scoring debut Down Under in Melbourne aside, he has struggled to make much of an impression, generally trailing young team-mate Sebastian Vettel in both qualifying and the races.

Scuderia Toro Rosso co-owner Gerhard Berger explained that he had granted Bourdais half a season's grace - but that now, as the final races approach, it is time to deliver. In qualifying inside the top ten in each of the last two grands prix - in Valencia and Spa-Francorchamps this weekend - and in out-pacing Vettel in Belgium to place ninth on the starting grid, the man from Le Mans is finally beginning to answer his critics.

"On a good day I am two tenths behind Sebastian," the 29-year-old told the official Formula 1 website, "but on a bad day I am five tenths off, which is way too much. It's not that I'm getting my a*se kicked every fortnight - but it's not far from it."

One major explanation for Bourdais' difficulties in 2008 is the fact that since the introduction of STR's new car in Monaco back in May, he has struggled to gel with it - as the Ferrari-powered STR3 has proven to be much more in-tune with the driving style of Vettel than his own.

"Probably it is one of my weaknesses," he confessed, "not being able to adapt my driving style to cars I don't really like. Sebastian is much more flexible. That is probably his number one quality I would say, as he really has been able to step up the game and find ways around the problems, whereas I am just kind of hitting the same wall a bit."

Those problems have seen Super Aguri F1 refugee Takuma Sato as well as GP2 Series front-runners S?bastien Buemi, Bruno Senna and Karun Chandhok all linked to the small Faenza-based outfit for 2009 - with no guarantee of Bourdais' own security at the team. He recognises that from hereon in, the ball is entirely in his court.

"That's the game of Formula 1," he mused. "You need to show some results if you want to stay where you are."