small potatoes

US /smɔl pəˈteɪtoʊz/
UK /smɔl pəˈteɪtoʊz/
"small potatoes" picture
1.

something or someone considered unimportant or insignificant

:
Don't worry about that minor issue; it's just small potatoes compared to the main problem.
His previous achievements were small potatoes compared to his latest breakthrough.