Kubica pleased with fourth, not with lap

"My qualifying was quite ok. I'm happy with P4 but not with my final lap," said Kubica, who is expecting a very difficult race tomorrow.

"I was struggling a little bit with the overall grip. In the last stint of Q3 I had hardly any grip in the first sector. I lost quite a lot of time there.

"Felipe Massa was in front of me on his out lap, perhaps the tyres didn't reach the right temperature. However, the race will be a completely different story.

"It will be a very tough one. The track is very bumpy and very demanding. The tyre degradation will be a crucial factor," added the BMW Sauber driver.

Teammate Nick Heidfeld was sixth fastest today, the German declaring himself pleased with his showing.

Like Kubica, however, Heidfeld reckons tomorrow's race could be the most challenging of the season.

"I'm quite happy as I had a good lap," he said. "Right from the first practice sessions on Friday we have made several changes and most of them were right. The car has improved and I have familiarised myself with this circuit and also improved. Tomorrow a good start will be crucial.

"Overtaking is extremely difficult here because the track is so narrow and off line dirty and even bumpier. This could become the most demanding Grand Prix of the year."