on one's knees

adjective2

1. •
   Kneeling, begging or as if begging.

   • For god’s love do not turn away—if you have knowledge. We suppli­ants implore you on our knees. — 1928
2. •
   (figurative) On the verge of collapse; at the mercy of someone.

   • Hungry Berbatov then converted a Giggs cross for his third before Nani slotted a fifth with Birmingham on their knees. — 2011