Upstaging
From Wikipedia, a free encyclopedia written in simple English for easy reading.
If a person upstages another person it means that he or she makes an audience pay attention to him or her instead of to the other person. The word comes from the theatre but it can also be used for situations outside the theatre.
To understand what "upstaging" means: imagine a man and a woman on a stage in the theatre. The man is talking or singing to the woman. The man is standing stage centre (in the middle of the stage). The woman is standing downstage (the part of the stage near the audience). Because she is facing the man she has her back to the audience. The man is facing the audience. Dramatically he is in a strong position. The audience are watching him.
Now the woman starts to walk upstage (towards the back of the stage). This means that the man, who is still talking or singing to her, has to turn his back to the audience in order to face the woman. The woman is now in a strong position dramatically while the man looks silly. The woman has upstaged the man.
Sometimes actors do deliberately upstage another actor. This is, of course, a very unkind thing to do and it is very unprofessional behaviour.
Sometimes we might talk about upstaging even if it is not in the theatre. Imagine a speaker who is talking to an audience. A little dog comes along and starts to do funny things that makes the audience laugh. They are not listening to the speaker any more. The dog has upstaged the speaker.