Research aims to identify the impact of athletic stress on biomechanics of movements of the joints in the lower extremity during performing compound skills by the junior soccer player. The researcher used the descriptive method through using kinematographic analysis. The research was applied to a sample of (6) junior soccer players selected intentionally from Mansoura Sports Club. The researcher used the following physical tests: Standing Balance Test - Illinois Agility Test - Quadrant Jump Test - Vertical Jump Test Isometric Leg Strength Test, in order to identify the level of stress in addition to skill tests as well (receive&kick). This study used kinematographic analysis by using Simi Motion System. The researcher used the pre- and post- measurement before and directly after the match and before the players could recover. The most important results were that the averages values of the biomechanical variables and the physical measurements confirm a decrease in the post-measurement test than the pre-measurements in all the skill performance phases. Also, the time of performing the two skills under study was shorter in the pre-measurements, which confirms in general that the research sample was significantly influenced by stress. There is a significant correlation between the physical and the biomechanical variables expressing stress. In addition, there is a correlation between the physical and biomechanical variables and the skill performance phases in terms of post-measurement, which influences the effectiveness of the skillful performance skills in soccer for the research sample.