Why is the scope operator for std namespace not required in this case?

Question

I tried the following:

#include <vector>
#include <algorithm>

int main ()
{
    std::vector<int> myVector = {1, 2, 3, 4};
    all_of(myVector.begin(), myVector.end(), [](int i){return i;});
}

expecting a compilation error as I did not put std:: in front of the all_of function, which is a part of the standard namespace. However contrary to my expectation, the code compiled. Why is std:: not required in this case; does it have to do with using myVector in the all_of function?