upstaging

Short definition from Wiktionary

Verb

1. 1
   present participle and gerund of upstage

Noun

1. 1
   A situation where somebody or something is upstaged; thus: A stealing of the spotlight, as (or as if) one performer eclipses another in the audience's attention.
2. 2
   A situation where somebody or something is upstaged; thus: An increase in the stage of a case of a disease (usually a cancer), from a less-threatening to a more-threatening stage.