How to say: 'Yesterday was not...'

Question

The sentence I am trying to write: Yesterday was not Monday, it was Sunday.

The Spanish translation I came up with: Ayer no fue lunes, era domingo.

The translation section from this site gave me:

Ayer no fue lunes, era domingo.

Ayer no era el lunes, era el domingo.

I want to know if it could be written (el is in parenthesis because I do not know if it would or would not be used in these sentences):

Ayer no fue lunes, era (el) domingo.

Ayer no fue (el) lunes, que era (el) domingo.

Ayer no era (el) lunes, era (el) domingo.

Or would it be written in another way?

Answer 1

Ayer no era el lunes, era el domingo.

EDIT: It's fue not era as I put because as somebody below me has pointed out the action has been completed. I've gone dumb.

Ayer no fue el lunes fue el domingo.

Whoops!

Thank you :). - interconnected, Jan 29, 2012

Sorry, but I'm wrong. It should be FUE as it's been completed. I don't know why I put ERA. Stupid me. :) - soytommy, Jan 29, 2012

Answer 2

Ayer no fue lunes, fue domingo.

The preterit is needed in this case because we see that word ayer, which "triggers" the preterit because the action is complete.

You are correct. :) I've gone dumb. - soytommy, Jan 29, 2012