Edward Gumm, 36, a Chelsea fan was struck from behind as he entered stadium before the derby game against Tottenham.
Father of two, Edward Gumm had arrived at the ground with his sister and was near the Peter Osgood statue behind the West Stand when he was assaulted, about 15 minutes before kick-off, the Daily Mail reports.
Mr Gumm, 36, of Bexley, south-east London, was pulling his tickets from his wallet when he was struck from behind, possibly with a blunt weapon such as a knuckle duster.
The father-of-two was knocked unconscious and suffered severe concussion and police are appealing for witnesses to come forward.
Mr Gumm’s wife, Georgia issued a statement on a fans’ forum which said: “We are as a family so pleased he’s alive but we cannot believe how such a savage and unprovoked attack could have occurred inside the grounds of Chelsea FC.
“My husband has been supporting Chelsea as a season ticket holder for 31 years and has never been involved in any form of accident or trouble. We hope this mindless thug is caught.
“Ed is a loving husband and a wonderful father to two beautiful girls and very close to his sisters and brother and elderly father.”