MLA in-text citation question?

If you have a short story in an anthology, do you put the author's name (in this case, Ana Maria Matute) or would you put the "author" of the book (Mendez). I put the author of the book and not the short story, and my professor looked at it and said nothing about it was wrong, but it seems odd to me. Should I put Matute instead of Mendez?