Piano accompaniment as a form of collaborative music performance is an activity undertaken in many settings, with participants bringing many levels of expertise to the activity. As a piano accompanist I have always been interested in exploring the characteristics of my collaborative performance experience that are particularly enjoyable and satisfying. This paper discusses some of the results of an autoethnographic study into the phenomenon of flow during collaborative music performance as a piano accompanist. Flow was first described by the American psychologist Csikszentmihalyi in the 1970s and is used to describe those best moments in our lives when everything seems to come together seamlessly. His research found that people could experience flow if the challenges they faced could be met with the right level of skill. The results of the autoethnographic study found that for a piano accompanist there were a number of specific challenges and skills that needed to be in balance so that flow could be experienced. This paper will discuss one of the concepts in the challenge-skills balance: the music reading skills that are of particular importance to meeting the challenges for a piano accompanist, and how the maintenance of the challenge-skills balance in this area can facilitate flow in collaborative music performance.