comer

One in a race who is catching up to others and shows promise of winning.

An ambitious person; one who is catching up in some contest and has a likelihood of victory;

This guy is is a real comer.

The transition from comer to also-ran can be quick.

One who arrives.

The champ will face all comers.

It was soon apparent that no every day comer was at the door. One servant whispered […] it was the bishop […]

A surname.