underdog

(noun) a competitor that has almost no chance of winning

Example Sentences:

Canada is the underdog in their soccer match against Brazil.

Brazil is the underdog in their hockey game against Canada.

From the News:

Underdog Danes set to face England

Media:

Similar idioms:

1. dark horse
2. hat trick
3. fly in the face of
4. newbie
5. put together
6. rough-and-tumble
7. rough-and-tumble
8. about face