supporting act
compound.compound. a singer or band that performs before the main star at a concert.
compound. an entertainer or group that performs prior to the headline performer at a concert or show. The term implies a subordinate professional status relative to the main attraction.
The supporting act was actually better than the main band.
We arrived early to see the supporting act, as they are a local band we really like.
While the headliner garnered the most media attention, the supporting act delivered a surprisingly nuanced performance that captivated the early arrivals.
often used in the plural when multiple bands play before the main event.
contrast with 'headliner' or 'main act'; note that in American English, 'opening act' or 'opener' is a more common synonym.