Workflow auto populate new record in lookup

Hi,

I’m working on system workflow, I have created a workflow on Account entity.

In Account entity I have a field called Approved Account field is check box.

Once I checked that check box workflow should trigger and create a new opportunity.
Workflow is working fine and creating a record.

I have a lookup field on the Account entity called Recent Opportunity.
lookup to Opportunity entity.

Once work flow triggered and created a new opportunity that opportunity I need to auto populate on the opportunity lookup which is on the account entity.

How can I achieve this if any suggestions that should be highly appreciated. 

Thanks,