darkhorse
nounUK /ˈdɑːk.hɔːs/
US /ˈdɑːrk.hɔːrs/
A dark horse is someone who surprises everyone by winning or doing well.
Nobody expected the quiet boy to win the race, but he was a dark horse.
RELATED WORDS
OTHER MEANINGS
2. A horse with a dark coat whose racing ability is not yet known.
The trainer entered a dark horse in the race to see how fast it could run.
3. A person who keeps their talents or plans hidden from others.
She seemed shy, but she was a dark horse who had read every book in the library.
4. Someone who is not well known but may unexpectedly succeed.
The new player was a dark horse in the tournament and beat the champion.