Dic: something is in the bag, you have it in the bag

• Once we'd scored the third goal, the match was pretty much in the bag.
• Nobody knows who'll get the job, despite rumours that Keating has it in the bag.
• When the score reached 12 to 2 we knew the game was in the bag.

in the bag :

1. (informal) if something is in the bag, you are certain to get it or to achieve it.
   [Usage notes: Someone who hunts puts what they have killed in a bag.]
   
   
2. safe or certain.
   [Usage notes: usually said about the result of a competition or election]

.... http://idioms.thefreedictionary.com/in+the+bag