Reserves and Second fiddle

Reserves noun - Civilians trained as soldiers but not part of the regular army.

Second fiddle and reserves are semantically related In some cases you can replace phrase "Second fiddle" with "Reserves", this terms are similar.

Second fiddle noun - A secondary role or function.

Reserves and second fiddle are semantically related in secondary role player topic. You can use "Reserves" instead a noun phrase "Second fiddle".