Jenson Button has admitted that he does not understand why he was unable to make it through to the final phase of qualifying at the Spanish Grand Prix, but insists that he still has a chance of scoring good points in Barcelona.

The Briton had been fastest of all in Friday practice, after fitting a set of the softer Pirellis to a McLaren that exhibited excessive understeer for much of the day, but joined Red Bull rival Mark Webber in being outside the top ten as the chequered flag fell on a turbulent second qualifying session. With 14 changes of order in the 'drop zone' during the final four minutes of action, it was always likely that one of the bigger names may be caught out, but Button admitted that he did not expect to be in that position.

"I expected quite a bit from qualifying today, so I don't really understand what went wrong," he sighed, "We were quickest on the soft tyre yesterday, and I thought we'd be reasonably competitive today too - but that wasn't the case, and we don't really know why. I just struggled with a very different balance from yesterday. I had oversteer all through qualifying, then, on my final run - when we actually added more front wing - I had understeer!"

With McLaren team-mate Lewis Hamilton being stripped of pole position after stopping out on track to disguise a 'refuelling problem' that left him in danger of failing to provide the necessary sample to the stewards, Button will start the fifth round of the season from the outside of row five, but remains hopeful that his team-mate's showing can bode well for raceday.

"The speed is in the car, as Lewis showed, [so] I guess you'd just have to describe today as a difficult day at the office," he said of his qualifying effort, "It's not a perfect day when you qualify in P11, but I hope we can work out what's happening with the balance for the race tomorrow."