Reading the blog for the Vuelta a España, I find the entry
Michael Storer (Team DSM) se marcha solo a por la victoria a 3 de meta. 17" sobre Verona y Sivakov y 4 minutos al pelotón.
I know what it means. He took off alone for victory, but why is it a por la victoria and not just por la victoria? I have looked up the entries for both a and por in the DLE, but without finding any example there. I do not think it can be a typo since the heading for that entry was
Storer se marcha a por el triunfo