Initial validation of the ITF World Tennis Number (WTN) on-court assessment

This study validates an initial on-court assessment for the International Tennis Federation (ITF) World Tennis Number (WTN), designed for players without prior ratings. The research followed a multi-phase approach: (1) literature review, (2) ITN-WTN equivalence analysis, (3) evaluation of existing on-court tests, and (4) validation with 106 recreational players across six countries. Pearson’s correlation and stepwise multiple regression identified ITN as the strongest predictor of WTN (r = -0.45, p < 0.05), followed by serve (r = -0.39, p < 0.05) and volley (r = -0.31, p < 0.05). The final model (β = -0.0464, p < 0.001) explained 19.8% of WTN variance. These results confirm the ITN-based on-court test as a reliable tool for assigning initial WTN ratings. The implemented tests assessed serve, groundstrokes depth, groundstrokes accuracy, and volleys. Their strong correlation with WTN supports their validity in structured player classification. This assessment offers a standardized, accessible approach for players without match history, ensuring a fairer rating system.