Saved form (in draft folder) cannot be accessible by the managers. So I don't think your requirement can be accomplished.
However, it is a general practise to have the Manager's approval before a form proceeds further. In this case, the user fill-in the form and submits which will reach the Manager for Authorization. If authorized, the workflow move forward or(if rejected) just completes. This might be a typical scenario for your requirement.
Nith