Pass a member function as Compare operator for C++ standard library algorithm

In my code I have now something like

    Foo bar;
    std::unordered_set<Foo>::iterator minElement =
      std::min_element(std::begin(mySet),
                       std::end(mySet),
                       [&bar](Foo const &lhs, Foo const &rhs) {
                         return bar.myWeakLessOperator(lhs, rhs);
                       });

I wonder wether it exists a way to simplify it by passing directly the member function myWeakLessOperator (that is not static) instead of writing a lambda function just to make to call.

I would like to obtain something like

    Foo bar;
    std::unordered_set<Foo>::iterator minElement =
      std::min_element(std::begin(mySet),
                       std::end(mySet),
                       /* something that rely to */ bar.myWeakLessOperator);

Any idea if it possible and how to do it ?