Man Utd physios left red-faced as Casemiro's personal doctor finds undetected potentially serious hamstring injury

The midfielder was initially deemed fit to play by the club's staff ahead of their 4-3 quarter-final victory at Old Trafford on Sunday. However, he was soon ruled out as United confirmed he had sustained a "muscle injury", and he has since withdrawn from the Brazil squad for the upcoming friendly against England.

During training the day before the showdown against the Reds, the midfielder felt pain in his hamstring - the same injury that had ruled him out for almost three months earlier in the season. After United's doctors failed to pick up on it, Trivelareports he consulted his own doctor in Barcelona who diagnosed him with a minor injury that could become a bigger problem.

Despite pulling out of the national team, the 32-year-old travelled to London to meet his Brazil team-mates ahead of their friendly against England. United will hope that he recovers well before they return to Premier League action after the international period.

The former Real Madrid star will miss out as the Selecao take on England and Spain. He could be back in action when United visit Brentford in the Premier League on March 30 as the Red Devils look to keep up their fight for a spot in next season's Champions League.