Practice is one of the most important predictors of skill. To become an expert, performers must engage in practice for a prolonged time to develop the psychological characteristics necessary for outstanding performance. Deliberate practice (DP), that is focused repetitive activities with corrective feedback, is particularly beneficial for skill development. The amount of accumulated DP differentiates experts and novices. However, the predictive strength of DP weakens considerably when it comes to differentiating between differently skilled experts, leaving a way clear for other non-practice related factors to exercise their influence. In this paper, we demonstrate using a large sample (388) of elite youth soccer players that one such factor, the personality trait of grit, predicts expertise level both directly and indirectly. Grittier players accumulated more time in coach-led team practice, the activity, which is arguably closest to DP in team sports, which in turn predicted the skill level. Other practice activities, such as self-led training or playing with peers, were not predictive of skill level, neither were they influenced by grit. Grit, however, continued to exert a direct positive influence on the skill level of players even after accounting for the hours of DP accumulated. Overall, a standard deviation of change in the grit score resulted in at least a third of standard deviation improvement in skill. Our findings highlight the need for the inclusion of additional factors in theoretical frameworks in situations where the predictive power of traditional expertise factors, such as practice, is limited.