Raphael Varane has revealed he played in some of the biggest matches of his career while suffering the effects of concussion - and withdrew from a Manchester United game this season with similar symptoms.
The French defender, 30, told L'Equipe that he played in his country's 2014 World Cup quarter-final defeat to Germany after taking a blow to the head, which left him with 'eye fatigue'.
Varane also blamed his horror show in Real Madrid's 2019-20 Champions League last-16, second leg loss to Manchester City on concussion, admitting he 'felt like a spectator'.
He said concussion symptoms forced him to withdraw from a United fixture this season, telling the French sports newspaper: 'During a match, I performed a series of headers, and in the days that followed I felt abnormal fatigue as well as severe eye fatigue.
'I reported to the staff that I was not fit to play and they strongly recommended that I not play. I took a test from a doctor, the results of which were passed on to the staff and I did not play for following match.
Manchester United defender Raphael Varane has admitted to playing in huge games while suffering the effects of concussion - and has pulled out of matches this season
The central defender is at heightened risk of concussion problems given the number of balls he is required to head away
In an interview with French newspaper L'Equipe, Varane said he now is more wary of playing after taking blows to the head
'But if I hadn't asked to take these tests, I probably would have been lined up a few days later and, to be honest, I felt bad that I didn't play the next game because of a migraine.'
Speaking out to help awareness of the potentially fatal consequences of playing with concussion symptoms, Varane spoke of two significant matches in his illustrious career in which he played when he really shouldn't have done.
Having taken a blow to the temple in France's 2014 World Cup last-16 match against Nigeria, which left him playing the remainder of the game 'in autopilot mode', he started the next game against Germany.
'I wasn't going to miss a World Cup quarter-final because I was a little tired,' he admitted.
'I felt eye fatigue. Looking back, I say to myself: If I had known it was a concussion, would I have said it, even if it meant not playing this match?
'The staff wondered if I was suitable. I was diminished, but ultimately I played and rather well, even if I lost this duel against [Mats] Hummels [for Germany's winning goal].
'What we will never know is what would have happened if I had taken another impact to the head. When you know that repeated concussions have a potentially fatal effect, you tell yourself that things can go very wrong.'
Varane played for France in the 2014 World Cup quarter-final against Germany after taking a blow to the head in the previous round
He endured a horror show playing for Real Madrid against Manchester City in the 2020 Champions League last-16 a few days after taking a blow to the head
Varane played in the match at the Etihad Stadium and made two costly mistakes
In July 2020, Varane took another blow in a LaLiga match between Real Madrid and Getafe, leaving him feeling 'without energy' ahead of the Champions League second leg against City.
In the 2-1 defeat at the Etihad, Varane lost the ball to Gabriel Jesus, who teed up Raheem Sterling to score City's ninth-minute opener.
Varane then made a further error when his headed back-pass fell short of goalkeeper Thibaut Courtois to gift Jesus a goal in the second-half.
'I felt it from the warm-up. I said to myself, 'wake up,' he said. 'I couldn't concentrate on staying in my match, I was like a spectator.
'The match went badly for me and, with hindsight, I realised it was linked to the shock I had suffered.'