伏兵

1. Origins, structure, and basic meaning

• Structure: 伏兵 is read as ふくへい and means either troops lying in ambush or, figuratively, an unexpected strong contender or dark horse.
• Basic usage: Use 伏兵の新人選手 for a rookie dark horse and 山道に潜む伏兵 for troops lying in ambush on a mountain road.

2. Common pitfalls and similar expressions

• Difference between 伏兵 and 奇襲
  • The former names hidden troops or an unexpected contender, whereas the latter names the act of launching a surprise attack.