datagridview - How to set by code value to a cell when editing a new row and before persisting data.

Question

I have datagridview1 and databindingNavigator1 both bound to databindingSource1

I wonder how to set a value by code to a cell in datagridview1 as soon as I click on the AddNew button of the databindingNavigator.

I tried datagridview1_RowsAdded event without success.

Thanks in advance.