## 1 Introduction  
Agility, though often acknowledged anecdotally as a crucial element in successful tennis performance, has not received extensive scrutiny or widespread acceptance within long-term athlete development training programs [1]. [PERSON] et al. [1] delved into the influence of growth, maturation, and training on both physical and psychological attributes. They emphasized that the incorporation of agility training throughout athlete development programs is imperative for enhancing the overall well-being of youth tennis players. Despite the scant research focusing on paediatric athletes and the positive effects of agility training on psychological performance in pubertal youth tennis players, recent models in Youth Physical Development [2; 3] underscore the pivotal role of a structured and methodical agility plan. This plan aims to develop various agility components at specific time periods aligned with growth and maturation stages, ultimately contributing to the physical and mental well-being of young athletes. Agility training involves exercises and drills that enhance a player's ability to change direction quickly, react swiftly, and maintain balance and coordination on the court. This type of training can indirectly impact emotional intelligence (EI) by improving a player's self-confidence, self-awareness, and ability to regulate emotions [4]. Recently, [PERSON] et al. [5] investigated the associations between agility and EI in college athletes. The study reported that a significant positive correlation between agility and EI scores was observed, suggesting that athletes with better agility also displayed greater EI. In addition, earlier studies [6; 7] discussed the relationship between CoD training and cognitive functions such as attention, decision making, and reaction time in elite and sub-elite U-14 soccer players. The authors showed a small-to-medium correlation between cognitive function and CoD performance. However, further intervention studies focusing on the effects of agility training on the development of EI are warranted. For instance, agility plays a crucial role in tennis, allowing players to swiftly respond to opponent's shots, cover the court effectively, and maintain balance while executing varying strokes. It also involves quick footwork, explosive movements, and agility. In the same way, agility is a critical aspect of tennis performance, as players need to quickly and efficiently move around the court to reach the ball and maintain a good posture for shot execution. Agility involves quick footwork, coordination, and balance [8]. Additionally, it has been shown that individual sports athletes, like tennis players, pose better reactive agility (RA) and CoD in lateral, semicircular and universal movement patterns, which are also highly associated with jump and sprint performance [9]. Furthermore, EI is a mental well-being factor that refers to individual proficiency to identify, comprehend, and control emotions and to recognise and respond appropriately to others emotional displays [10; 11]. In the context of sports, such as tennis, EI plays a crucial role in athletes' performance, well-being, and overall success [12]. Research suggests that EI exerts a positive influence on the performance of tennis athletes [13; 14; 15]. High levels of EI enable players to stay focused, manage stress, and maintain motivation during matches [15]. By effectively managing emotions, tennis players can improve decision making, adapt to changing situations, and perform optimally while under pressure [16]. Furthermore, EI contributes to enhanced self-awareness, which allows players to recognise individual strengths and weaknesses, leading to targeted game improvements [13]. In this context, [PERSON] et al. [17] highlighted the effectiveness of the training program in improving agility-related skills and performance in tennis. Coaches can incorporate similar training methods and exercises to improve their players' agility, leading to better performance on the court.