Force India arrived to Italian GP venue Monza on the heels of a very strong run at Spa-Francorchamps, but has had a rough start to the weekend, both its drivers ending up outside the top 10 in FP2.

Said Perez: "Generally I haven't been very happy and comfortable with the car and balance. I think there is a lot of room to improve the mechanical balance out there, that is our target - to figure out a nicer balance for high speed to low speed.

"This weekend we are having more doubts about where to put the mechanical balance together with the aero balance.

"The [tyre compounds] are working very different, low fuel to high fuel, they are requiring different things, So there is a lot of analysis to be done and a lot of thinking/decisions to be taken for tomorrow.

"It was a bit of a shock to see that McLaren, Haas and Williams, they seem to have the upper hand on us this weekend. Hopefully we can find some time and some nice tuning on the balance tonight."

Perez subsequently noted he was particularly surprised by the early pace of his former team McLaren.

"They can be strong. I was surprised with their pace because, in Spa, I could see they were lacking some straightline speed. But they seem to be alright here."

Additional reporting by Jonathan Noble