Steal The Firewood From Under the Pot (釜底抽薪) from the Thirty-Six Stratagems (三十六計)

釜底抽薪

不敵其力，而消其勢，兌下乾上之象。

"When faced with an enemy too powerful to engage directly you must first weaken him by undermining his foundation and attacking his source of power."

Quoted from Chinese Classics and Translations