~はいうまでもなく (not to mention)
grammar2 sentences
The pattern ~はいうまでもなく ('needless to say X / not to mention X / let alone X / X goes without saying'). Establishes one item as a given/obvious before adding something surprising or additional. AはいうまでもなくBも = 'not only A (which goes without saying) but also B.' More formal/literary than ~はもちろん.