AD authenticate against user portion of UserPrincipalName

Is it possible to AD authenticate against user portion of UserPrincipalName?
So if it’s user@corp.domain.com, just user?

yes, but you’ll need to use SamAccountName instead of userprincipalname in your mapping.

We’re using sAMAccountName for something else :worried:

So we’d need to be able to use the user portion of UPN if possible.