Sport coaching has traditionally been seen as a techno-rational activity. In recent years, there has been a 'subjective turn'. Intuitive, as well as situation-specific interpretations are today perceived as necessary to handle complex, dynamic and often unpredictable sport environments. While a considerable body of research has attempted to understand coaching practice, research on intuitive and situation-dependent praxis is only emerging. Phronesis - mostly defined as practical wisdom or practical rationality - has been put forward as a useful theoretical concept to frame such coaching practice. In this contribution, we employ phronesis as part of sustainability science to consider the coaching of one top-level middle-distance running coach. Observations, informal talks and semi-structured interviews produced the empirical materials for this analysis. The results suggest that the coach's practice was guided by both techno-rational and phronetic knowledge. While techno-rational knowledge manifested itself in a focus on time and control, the latter was reflected in a concern for impact, focus on community, authenticity and modesty. From a phronetic perspective, these characteristics can be seen as morally just and important precursors for sustainable sport.