1. hard nut to crack-
E.g: The game on Saturday will be a hard nut to crack
2. At the eleventh hour- Last moment or too late.
e.g: She has a habit of doing things at the eleventh hour.
3. chicken out- To be afraid of doing something
He was going to take the exam but he chickened out at the last moment.
.4. juncture- A point of time
E.g: At this juncture, it looks like they are going to fail the exam.
5. eavesdropping- Act of secretly listening to something private
e.g: I get to know about his eavesdropping and confronted him.