マットに沈しずむ

expression, godan verb (-mu)

be knocked out; be overwhelmed; be flabbergasted

Idiomatic expression literally meaning 'to sink into the mat', used figuratively for being completely defeated, shocked, or at a loss for words. Often used in sports or competitive contexts, but can apply to any overwhelming situation.

• 彼かれのパンチで相あい手てはマットに沈しずんだ。

  His punch knocked his opponent out onto the mat.

• その質しつ問もんに彼かれはマットに沈しずんでしまった。

  He was completely floored by that question.