Kimi Raikkonen was left mystified by how difficult his Ferrari Formula 1 car became to drive during Italian Grand Prix qualifying.
The Finn failed to reach Q3 and was only 12th quickest, which will become 11th on the grid due to Toro Rosso driver Daniil Kvyat's penalty.
That was despite an encouraging run through Friday practice.
"We changed the car a little bit, but it's hard to believe that those small changes made it as difficult as it was," said Raikkonen.
"We had a good weekend on this side and we had no issues. Things were running smoothly, as they should always, and then we had difficulties to get grip in qualifying.
"For some reason I kept locking the fronts a bit and couldn't find how I could make one sector good but not all of them in a row. It just got difficult for some reason.
"It was a bit of a surprise for me, an unpleasant surprise.
"We have to try to look into the details a bit and hopefully find an explanation."
Raikkonen is still optimistic that he will be able to make progress in race trim.
"Obviously today our qualifying was not very good for me, but overall the weekend has maybe been a bit better than expected," he said.
"We knew that qualifying would be a little bit difficult compared to some of the Mercedes people. They usually make a bigger step for that, and then it comes back a little bit for the race.
"We had a good long run yesterday, so I 100 per cent believe that we can do a much better race.
"Do we have enough speed to overtake people? We will know tomorrow. But I believe that we should be stronger than today."