Lewis Hamilton replacement Sergio Pérez knows he must produce instant results at McClaren after Sauber switch McLaren is always a guarantee, so I have to work very hard. I have to give everything to my team and I am ready to do that, once I have finished this season. But the former GP2 racer acknowledges he will be under big pressure replacing 2008 champion Hamilton, who he rates as one of the quickest drivers in the current field. "Of course I rate Lewis as one of the fastest drivers on the grid so it will not be easy at all," he said. I know he has very big shoes to fill, and I will work as hard as possible to give the best results and win the championship with this great team. For much of the season Ferrari had seemed a more likely destination for Pérez, who was part of the Italian team's young driver programme. But Ferrari president Luca di Montezemolo publicly questioned whether Pérez had the maturity to race for the Prancing Horse. Pérez, who also revealed his talks with McLaren had begun weeks ago, well before Hamilton informed the team he was leaving, rejected Di Montezemolo's comment and is ready to shine in a team that will give him a genuine chance of winning a world title. "Of course I respect him (Di Montezemolo)," he said. He is a person that I respect a lot. Maybe to drive for Ferrari you need more experience. I think he has his arguments, it's better you ask him what he meant by that. Maybe I am too young to join a team like Ferrari, I don't know. But I feel ready to drive for a top team and to fight for the championship.