The "What's this word/phrase?" thread

I need some help with a sentence from this short paragraph, about a guy almost getting punched in the face:

グーだ。ノーモーションで操り出されるグー。これでもかというくらいに見事な握り拳が俺の頬を掠めていった

I don't understand what's going on in the これでもかというくらいに part, can somebody please break it down for me?