Overplay your hand
Definition 1 of 1
Pro Tip 1/3Overconfidence Warning
The phrase often suggests someone's miscalculation due to excessive confidence in their position or abilities. 
He overplayed his hand by demanding a higher salary without having another job offer.
Pro Tip 2/3Cautious Strategy
Use it to advise someone to be careful not to show too much confidence or reveal all their advantages. 
In the negotiation, be sure not to overplay your hand too early.
Pro Tip 3/3Conversational Context
It is used more often in casual conversations rather than formal or academic contexts. 
Talking to his friend, Tom admitted he overplayed his hand during the poker game.