play second fiddle

From the second violin in an orchestra.

play second fiddle

1. (idiomatic, intransitive) To play a subsidiary or subordinate role to someone or something else.

   I think the VP is getting tired of playing second fiddle to the president, so if she's not promoted soon, she might leave.

   • 2011 December 15, Felicity Cloake, “How to cook the perfect nut roast”, in Guardian‎:

     Christmas queen Mary Berry's aubergine five-nut roast, from her Christmas Collection, is, as the name suggests, rather more focused on the nut side of things. Breadcrumbs play second fiddle to a medley of almonds, Brazils, chestnuts, pine nuts and pistachios which, although tangy with lemon juice and garlic, is outrageously dense. A single slice of this could leave you supine in front of the Queen's speech without even the wherewithal to reach for the remote control.