The Spaniard's first win of 2013 moved him third in the overall rankings, a success that he believes has blown the race for the crown wide open.
Alonso told BBC Sport: "At the moment I think Ferrari, Lotus, Red Bull and Mercedes are very similar. It is very close to call and a very open championship."
"We need to wait until maybe after the summer break or something like that to clearly see the real contenders.
"Hopefully we are in that group after the summer. Hopefully Felipe Massa can be in that group as well; that will mean that the car is going well, and I think at the moment Lotus, Red Bull and Mercedes are in the same position as us, let's say. I don't see anyone has a clear advantage."
Alonso finished second in Australia, but crashed out on the second lap in Malaysia.