I think the Australia match is 50:50; whoever wins the doubles should win; though Kyrgios or Tomic could push Murray close if he has an off-day.
And then it's either Argentina or Belgium - Argentina would be at home; Belgium away. So ideally, we'd want Argentina to win that one; but I think we'd be favourites against either of them; assuming Del Potro doesn't come back into some sort of form.