This study aims to investigate the effects of four-week astaxanthin supplementation on soccer-specific performance under fatigue in soccer players. Using a randomized, double-blind, placebo-controlled design, participants were assigned to receive either astaxanthin or placebo for 4 weeks. After the supplementation period, participants completed an exhaustive exercise protocol followed by assessments of soccer-specific performance, neuromuscular function, and fatigue-related responses. The study is designed to determine whether astaxanthin supplementation can attenuate fatigue-related declines in performance and improve recovery-related outcomes in soccer players.