I am writing an academic paper for submission to a journal. One of my co-authors wrote the following:

> __Theorem__ Statement of the theorem
>
> __Proof of theorem__ We first show the following result
> 
> __Lemma__ Statement of lemma used to prove the theorem

However, I think that it is more natural to present things in the following way:

> __Theorem__ Statement of the theorem
>
> We first show the following result which is used to prove the theorem:
> 
> __Lemma__ Statement of lemma used to prove the theorem
>
> __Proof of theorem__ blah blah

I understand that this is a subjective question so I am happy to mark this as community wiki if most people feel that it belongs there.