OBJECTIVES: This study aimed to determine the effects of mental fatigue on attention and groundstroke targeting performance in tennis players. METHODS: A total of 66 young male tennis players (age: 24.32 ± 2.46 years) participated in this randomized placebo-controlled crossover trial. Interventions included mental fatigue (MF), non-fatiguing effect (Placebo), and no mental fatigue (Control). The Stroop Attention Test (SAT) and Tennis Groundstroke Targeting Test (TGTT) depth and accuracy sections were administered before and after all interventions. Changes over time in normally distributed homogeneous data were determined using repeated-measures ANOVA (3×2), with Bonferroni correction applied for RESULTS: Post-test pairwise comparisons showed that the MF intervention significantly increased SAT completion times and SAT error scores ( CONCLUSION: This study demonstrates that acute mental fatigue decreases attention and tennis groundstroke targeting performance in male tennis players.