“下马威”，原指官吏初到任时对下属显示的威风（severity shown by an official on assuming office），后泛指一开始就向对方显示自己的威力（head-on blow at the first encounter）。

常用表达“给对手一个下马威”，英文可以翻译为“prevail over the opponent from the very first encounter”，或“secure a leading position over the opponent from the very beginning”。

例句：

新经理一来就来了一个下马威，开除了几个懒散的员工。

As soon as the new manager assumed office, he showed his ruthlessness by firing several slackers.

教练一开始就给每个球员来了一个下马威。

The coach begins by putting the fear of God in every ballplayer.