step up to
step up to (someone or something)
To move in front of or close to someone, something, or some position. He stepped up to the man and told him to back off. You'll need to step up to the line while getting your photo taken.
step up to something
to walk to something, especially a counter or a bar. Jake stepped up to the ticket counter and bought a single ticket for the balcony. When Wally stepped up to the ticket window, he learned that the show was sold out.