Ferrari star and F1 world championship leader Felipe Massa admits he is now up against it in the British Grand Prix, after wheel-changing troubles hamper his qualifying efforts at Silverstone.

Felipe Massa has acknowledged that his chances of triumphing in this weekend's British Grand Prix have taken something of a nose-dive after lining up just ninth on the grid at the end of a troubled qualifying session at Silverstone - as Ferrari have launched an investigation into just what went wrong.

The Brazilian had lapped on almost the same pace as defending world champion team-mate Kimi Raikkonen - who eventually wound up third-quickest - in both Q1 and Q2, but was badly hampered by a botched tyre change when it really counted in Q3.

The 27-year-old - already a three-time winner this year - admitted that the delay had cost not only his chances of starting considerably further up the order - but could also quite possibly cost him, on Sunday, his world championship lead.

"It's a real shame ending up ninth on the grid because of a problem with my pit-stop," he rued. "I lost so much time as my mechanics had trouble changing the right rear wheel, and I was unable to start my second qualifying run. I think I could have done a good time - maybe not enough to take pole, but at least good enough for a place on the front two rows.

"There was a lot of wind today, the balance of the car was not as good as yesterday and we were not as quick as at last week's test. Tomorrow I can definitely expect to be fighting all race-long to move up the order and I will do all I can to bring home a good result, but it won't be easy."

The Scuderia's team principal Stefano Domenicali and technical director Luca Baldisserri were both equally frustrated by the problem - and adamant that it must first be diagnosed and then not be allowed to be repeated.

"This is definitely not the result we expected," Domenicali admitted, "nor the one we wanted. Problems such as the one that befell Felipe are serious, and I am very sorry for him as we prevented him from giving it his best shot.

"On top of that, we need to understand why our performance - even taking into account all the unknowns regarding the various strategy choices - was not up to our usual standard.

"Nevertheless, this is only Saturday afternoon and we still have the race ahead of us. We are up against very strong opponents, but we will also be doing our utmost to bring home a good result."

"This is definitely not a pleasing result," concurred Baldisserri, "both in terms of performance and the work of the team. What happened at Felipe's pit-stop, which incidentally has nothing in common with what happened on the grid in the Monaco Grand Prix, will have to be investigated thoroughly as we cannot let it happen again.

"Compared with last week's test it seems we have taken a step backwards, and this is another thing we will have to look at and try to understand."