2 selection buttons 1 preferred but with different input types

I have 2 login forms in the same page: login with username&password, login with emailaddress&password.

I separated forms with tabs but 1 of the login forms is always selected as default behavior of a tab.

The one with the username&password is the default selected form.

However people type their email address to the form that I ask for username&password and I got a lot of faield login attempts.

I thought I could have an accordion menu that are collapsed as default or with navigation pills. Another option would be having 2 buttons and when clicked the login form open for each of them.

Any suggestions?