Nico Rosberg suspects a bad set of tyres cost him the chance of a strong result in the Italian Grand Prix last weekend.
The Mercedes driver qualified in sixth position, but said he was struggling with a set of tyres which lacked grip.
He reckons that was confirmed at the start, where he dropped down to 11th place.
While he struggled during his first stint, Rosberg flew once he switched to new tyres, eventually finishing in seventh position behind team-mate Michael Schumacher.
The younger German driver said he was encouraged by his car's pace during the weekend, but he reckons the first set of tyres cost him dearly.
"It was a positive weekend for us, because performance wise the car was looking good both in qualifying and the race," Rosberg said during his post-race video blog.
"For me I think in the end I was unlucky. In qualifying I just had a tyre set that didn't have any grip so I was a bit slow and ended up sixth, which still is OK.
"The fact that the tyre grip was no good was confirmed in the race because already from the start there was no grip at all.
"I lost five positions although all the settings were perfect, and I had no grip also in the first stint. So that was a tough start to the day.
"But then we came into the pits and put some new tyres on and from then on it was fantastic.
"I had a great balance in the car, really fast, overtaking lots of people, fastest lap of the race one after another, so that was cool and I was motivated to make up as many positions and come home in seventh right behind Michael, so that was OK."
- Nico Rosberg