blue bossa

is an extremely intractable piece, in a way one of the most diffucult pieces by Kapustin. Though we need to be careful comparing tthe degree of echnical / mechanical difficulties, it's more than prokofieff sonatas (late) and scriabin etudes. The primary source of difficulty lies in the creative movements on top of Kapustin's idiom. Therefore you need not only diligence but also creativity (meaning trying something new) at practice. I have only three weeks to perform that piece in public...