Can I Get Into a Top PhD Program Despite a Few Bad Grades?

[Salah93]

Hi,
I am an italian physics student. I know that this is a recurrent topic but I want some specific advice.
This year I am completing my third year of university to get my bachelor degree. Then I have to get my master. In these three years I got a lot of very good-top grade, and 2 average-bad grades(maybe is a C or C+ in your system).
For now I am also in what here in Italy we call school of excellence, but maybe I going to go out for my last bad grade(because on of the rules of this school is no bad grades). But this doesn't matter now.
I have two years of university but counting for the phd applications say one and a half. I want to be got in one of the top 20 university in phd. In the case to make it in US I am quite sure to get a very good score in pgre(>900). But I red that also people with max grades in all sometimes are not accepted.
I want to start research with some professor and I am going to study a lot this year. For now I did cosmology. What I say, it was good but I don't really enjoyed. I thought that there is more math. Maybe is because I am at the beginning. Maybe I have to try something else, but this would be a 'lose' of time for phd application.

Is there still any possibility for me to get in a top school working very very hard?

Thank you

 

[Greg Bernhardt]

What courses were the poor grades in?

 

[Salah93]

Sperimental Physics 3 and Nuclear Physics and Geometry.

For now I want maybe to be a theoretical physicist in cosmology.