Modern football put important training load and stress on professional players. This case study reports autonomic dysfunction associated with clinical symptoms in one male professional football player. Beat-to-beat heart rate (HR) during an orthostatic test (5min supine - 5min standing) was recorded two days before each of a series of 9 matches (1 match/week). Mean HR, power spectrum in the low- and high-frequency bands (LF and HF) were assessed. GNSS allowed recording of total distance, acceleration/deceleration above 2 m/s, video allowed technical assessment (number of passes, successful passes to final third, number of duels and duels won) during the matches. Supine HR (range 38.9–40.9 bpm) correlated with passes and successful passes (R=-0.67, -0.79, respectively; both p<0.05), standing LF (range 494–6012 ms2) correlated with duels and duels won (R=0.81, 0.75, & p<0.01, p < 0.05 respectively). Log(HF) correlated with sprints (R=0.79, p<0.05), log(LF) correlated with total distance (R=0.75, p<0.05). Standing parasympathetic hypertonia was found on several occasions, which could be associated with the player fainting. Combining HRV and in-game performance indicators demonstrated how HRV could be useful in identifying fatigue profiles associated with decreased performances and clinical symptoms.