be waiting in the wings

be waiting in the wings

to be ready to be used or employed instead of someone or something else
Usage notes: In the theatre, the wings are the sides of the stage which cannot be seen by the people watching the play, where actors wait until it is their turn to walk on to the stage.
The rumour is that Green will be sacked and Brinkworth is waiting in the wings to take over as manager.
See play a waiting game
See also: waiting, wing