SFINAE with functions and emulating partial template specialization

I am trying to make a function X that specializes when a member function Y is provided and if the member function Y is not provided the function X uses the global non member function Y to achieve the same effect.

I am currently trying to achieve this with the following code

template <typename Container, typename std::enable_if_t<std::is_same<
            decltype(std::declval<Container>().y()),
            decltype(std::declval<Container>().y())>::value>* = nullptr>
void do_something(Container&& container) {
    return std::forward<Container>().y();
}

template <typename Container, typename std::enable_if_t<!std::is_same<
            decltype(std::declval<Container>().y()),
            decltype(std::declval<Container>().y())>::value>* = nullptr>
void do_something(Container&& container) {
    return y(std::forward<Container>(container);
}

But in the case when the container has both a member function y and the global non member function y also works on it. There is a compile error because for the second version of the function the template argument is ill formed because a member function y is needed.

Any idea how I can go about resolving this issue?