up one's sleeve

(of a strategy, idea, or resource) kept secret and in reserve for use when needed

作为锦囊妙计的；留作一手的

he was new to the game but had a few tricks up his sleeve.

他虽不熟悉这项运动，却自有锦囊妙计。

wear one's heart on one's sleeve

he was new to the game but had a few tricks up his sleeve.

他虽不熟悉这项运动，却自有锦囊妙计。

up (one's) sleeve

Hidden but ready to be used

隐藏起来但准备使用的

I still have a few tricks up my sleeve.

我还有几种手段藏而待用呢