Abstract：The transition from junior to professional for young tennis players is a critical issue for professional teams, and data from performance analysis of tennis matches provides an important basis for players or coaches seeking to implement and modify their strategies for success. The 2021 US Open women's singles final match featured 18-year-old British player Emma Raducanu and 19-year-old Canadian Leylah Fernandez. Raducanu defeated Fernandez to win the title that year. The purpose of this study is to compare and analyse key performance variables within three categories (serve, return and rally) as executed by these two junior players on the road to the final. Data on thirteen matches of the 2021 US Open, released by the US Open and IBM SlamTracker, was collected and analysed. The number of matches included 6 matches for each final player before the final plus the final match itself. Results indicated that: Relative to their opponents before the final, Raducanu won a significantly higher percentage of points on service winners (62.26%) than Fernandez (36.56%), a higher percentage of total points won (56.07%) than Fernandez (50.18%), and a higher percentage of rally winners (60.00%) than Fernandez (48.79%). Only in return winners and return unforced errors did Fernandez have an advantage in terms of percentage of points. In conclusion: The trend of the two junior players who won through to the final was that Raducanu had the superior service advantage in the first phase of the game (higher than that of her opponents), while Fernandez improved her return advantage and increased the points from the baseline rally as the keys to win her matches. (Full text)