upstage (adv.)

1855 in theatrical jargon, "to the rear of the stage," from up (adv.) + stage (n.). From 1901 as an adjective, 1916 as a noun. The notion in the verb (1921) is of drawing attention to oneself (and away from a fellow actor) by moving upstage, so that the other actor must face away from the audience. Related: Upstaged; upstaging.

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Definitions of upstage from WordNet
upstage (v.)
treat snobbishly, put in one's place;
upstage (v.)
move upstage, forcing the other actors to turn away from the audience;
upstage (v.)
steal the show, draw attention to oneself away from someone else;
When the dog entered the stage, he upstaged the actress
upstage (adj.)
of the back half of a stage;
she crossed to the upstage chair forcing the lead to turn his back to the audience
upstage (adj.)
remote in manner;
he was upstage with strangers
Synonyms: aloof / distant
upstage (n.)
the rear part of the stage;
upstage (adv.)
at or toward the rear of the stage;
the dancers were directed to move upstage