Take a back seat
Take a subordinate or obscure position.
This phrase has a straightforward and literal derivation. It alludes simply to the back seats, of a coach, a theatre etc., being less prominent than the others. It originated in the USA in the mid 19th century. As we might expect, the earliest uses of the phrase merely refer to people sitting at the back. The first use that I can find of the figurative use of the phrase, i.e. one where no actual seat is occupied, comes from The Daily Wisconsin Patriot, May 1859:
"The despised foreign born slave - the much hated and often cursed 'Irish,' 'Dutch' and 'Norwegians,' must take a back seat in the exercise of all the foregoing announced privileges [voting, jury duty etc.] - no man of foreign birth can vote until two years after he shall have received his full papers."
See also; back seat driver.