The 2008 world champion told Sky Sports News: "The car felt good. The Red Bull looks quick, but generally our car felt good so I'll have to sit and try to understand where we can go quicker because generally I felt I was right on the limit everywhere and the car felt well balanced. So whether we have too much wing, we will have to wait and see."
He later added on Twitter: "Car feels good here today at Monza. Bit of work to do tonight but we are feeling confident and competitive."
The 28-year-old has started the last four grands prix from pole position.