Loris Karius sustained a concussion during the Champions League final which may have affected his performance, according to a leading expert on brain injuries.

The Liverpool goalkeeper had a disastrous game in Kiev, making two high-profile mistakes which directly led to Real Madrid goals as the Spanish side went on to win 3-1 and take their third successive European crown.

Real Madrid vs Liverpool, Champions League final - player ratings Show all 23 1 /23 Real Madrid vs Liverpool, Champions League final - player ratings Real Madrid vs Liverpool, Champions League final - player ratings Keylor Navas - 7 out of 10 Punched clear an early Liverpool shot and got down well to deny Alexander-Arnold’s strike. Should have acted more decisively for Mane’s goal. Solid performance in all. Getty Real Madrid vs Liverpool, Champions League final - player ratings Dani Carvajal - 3 out of 10 Forced off early with an injury. Prior to then, his notable contribution to the match was a wild cross-field pass to Sergio Ramos that ended up rolling out for a Liverpool corner. Getty Real Madrid vs Liverpool, Champions League final - player ratings Sergio Ramos - 7 out of 10 As ever, asserted his physicality well from the back – as seen with his challenge on Salah. Put in an important interception to deny Mane a second around 70 minutes. Getty Real Madrid vs Liverpool, Champions League final - player ratings Raphael Varane - 7 out of 10 Followed his captain’s lead. A solid force at the back. Getty Real Madrid vs Liverpool, Champions League final - player ratings Marcelo - 7 out of 10 Dangerous when roaming inwards. Misplaced a few passes but provided assist for Gareth Bale’s stunning volley. Getty Real Madrid vs Liverpool, Champions League final - player ratings Toni Kroos - 7 out of 10 A strong first half in particular, completing more passes than anyone else on the pitch. Kept Liverpool away from the ball in the second 45 minutes. Getty Real Madrid vs Liverpool, Champions League final - player ratings Casemiro - 6 out of 10 Not as smooth an operator as his midfield teammates but still played an integral role. Getty Real Madrid vs Liverpool, Champions League final - player ratings Luka Modric - 8 out of 10 Barely noticed him – which is exactly what he’s there for. Kept Real’s midfield ticking over smoothly with his tidy and slick passing. The footballing equivalent of an electric engine. Getty Real Madrid vs Liverpool, Champions League final - player ratings Isco - 5 out of 10 Missed a golden opportunity after the restart, hitting the crossbar instead. Failed to properly get going and was replaced just after the hour mark by Bale. Getty Real Madrid vs Liverpool, Champions League final - player ratings Gareth Bale - 8 out of 10 (substitute) The hero of the match. Scored arguably one of the best goals ever in a Champions League final to put Real back in front before killing off the game with a second. Showed his class and worth to Real. Getty Real Madrid vs Liverpool, Champions League final - player ratings Cristiano Ronaldo - 6 out of 10 Failed to have the same effect as he did in last year’s final. Had the opportunity to put the game to bed but, under pressure from Robertson, failed to find the target. Getty Real Madrid vs Liverpool, Champions League final - player ratings Karim Benzema - 7 out of 10 Smart and shrewd in clinching Real’s first. Not pretty in the slightest – not that’ll he mind. An industrious performance. Getty Real Madrid vs Liverpool, Champions League final - player ratings Loris Karius - 1 out of 10 A calamity. Essentially handed Real victory with two mistakes that shouldn't be made at this level. The less said about them the better. The German will be feeling the pain of defeat more than anyone else in this Liverpool side. It's important now he gets the necessary support he'll need moving forward. Getty Real Madrid vs Liverpool, Champions League final - player ratings Trent Alexander-Arnold - 6 out of 10 Hit a stinging strike inside Madrid’s box that was blocked by Navas. Got forward well and held his nerve in the biggest game of his career to date. Getty Real Madrid vs Liverpool, Champions League final - player ratings Dejan Lovren - 6 out of 10 Mixed performance. At times he read the game well and put in some important interceptions but this was offset against the occasional mistake. Faded away in confidence. Getty Real Madrid vs Liverpool, Champions League final - player ratings Virgil van Dijk - 7 out of 10 Calm and composed for much of the game. Held his line well to catch Real out with offside on a number of occasions. Not much he could do about the goals. Getty Real Madrid vs Liverpool, Champions League final - player ratings Andy Robertson - 7 out of 10 Looked comfortable up against Real’s front line. Showed real heart and desire with a last-ditch tackle to stop Ronaldo from scoring. Getty Real Madrid vs Liverpool, Champions League final - player ratings Jordan Henderson - 7 out of 10 Marshalled Liverpool’s midfield well to ensure the side maintained their high press for the first 60 minutes of the game. Never stopped running and did the basics well. Getty Real Madrid vs Liverpool, Champions League final - player ratings James Milner - 6 out of 10 Worked his socks off but flew under the radar somewhat. Getty Real Madrid vs Liverpool, Champions League final - player ratings Georginio Wijnaldum - 6 out of 10 Stepped in for the injured Alex Oxlade-Chamberlain. Injected a degree of energy to Liverpool’s midfield and worked hard in the press. Another player to fade away. Getty Real Madrid vs Liverpool, Champions League final - player ratings Mohamed Salah - 4 out of 10 The winger’s evening was brought to an early end in heart-breaking fashion after being fouled by Sergio Ramos. Up until that point the Egyptian had had little say on the match. Getty Real Madrid vs Liverpool, Champions League final - player ratings Roberto Firmino - 5 out of 10 Went missing for far too much of the match. Failed to deliver on the main stage. Getty Real Madrid vs Liverpool, Champions League final - player ratings Sadio Mane - 7 out of 10 A case of right time, right place for the forward, who met Lovren’s header with a close-range volley to draw Liverpool level. Later hit the post. Stepped up in Salah’s absence. Getty

Footage which later circulated on social media appeared to show Real Madrid’s captain Sergio Ramos connect with Karius’s head in an off-the-ball incident, which occurred only a few minutes before his first error.

Dr Ross D Zafonte of Massachusetts General Hospital, Boston carried out a “comprehensive examination” of the Liverpool goalkeeper on 31 May, and after reviewing footage of the game and hearing Karius’s recollections, concluded the 24-year-old suffered a concussion during the match.

In a statement, Dr Zafonte the concussion was linked to Karius’s performance in the final.

“At the time of our evaluation, Mr. Karius’s principal residual symptoms and objective signs suggested that visual spatial dysfunction existed and likely occurred immediately following the event,” the statement read.

“Additional symptomatic and objectively noted areas of dysfunction also persisted. It could be possible that such deficits would affect performance.”

Loris Karius endured a game to forget against Real Madrid (Getty)

The statement added that Karius had displayed “steady improvement” since the injury and was expected to make a full recovery.

Karius has been held largely at fault for Liverpool’s failure in the European showpiece and came out to take responsibility for his errors, tweeting the following day: “Haven’t really slept until now... the scenes are still running through my head again and again... I’m infinitely sorry to my teammates, for you fans, and for all the staff.

“I know that I messed it up with the two mistakes and let you all down. As I said I’d just like to turn back the time but that’s not possible. It’s even worse as we all felt that we could have beaten Real Madrid and we were in the game for a long time.

“Thank you to our unbelievable fans who came to Kiev and held my back, even after the game. I don’t take that for granted and once again it showed me what a big family we are. Thank you and we will come back stronger.”