Choosing Reviewers

You are the editor of a journal in field, F. You have just received a manuscript dealing with a potentially very significant phenomenon is a new subfield S within F. Although this subfield is widely expected to yield important results for the whole of F, it is so new that only a few research teams are really proficient in applicable research methods and techniques and each of those teams has its own theoretical approaches, approaches that differ significantly from one another. Because of the small number of investigators in this fast-moving subfield, you know that knowledgeable reviewers for the manuscript are to be found only among the author's past or present colleagues or among her competitors.

What do you do and how do you go about it?