The Football Association has said John Terry will be allowed to play in Saturday's Premiership clash against Portsmouth - as long as he is cleared to do so by a doctor.
The Chelsea captain was taken to hospital after being knocked unconscious in Sunday's Carling Cup final against Arsenal.
He was quickly released and returned to his team-mates to join in the victory celebrations.
It was still thought the defender would be forced to sit out the match at Fratton Park due to the FA's rules on players who suffer concussion.
But the FA has explained that its regulations merely stipulate that each individual must be assessed by a doctor.
A statement said: "Following John Terry's injury in yesterday's League Cup final, the FA can clarify that the rules on head injuries do not set down an automatic rest period for players suffering from concussion, but rather stipulate that each injury must be assessed individually by a doctor.
"The FA medical recommendations state that: `Since all head injuries are different in terms of the effects on the brain, no fixed time periods are applicable in professional football as to when the player should return to training and playing.
"The brain's response to the injury determines the time of return and playing and must be clinically assessed by the club medical officer or a specialist neurosurgeon/neurologist.
"The clinical rule is that no player should return to training or playing until symptom-free and sign-free at rest and on provocation."
The statement added: "The FA supplies clubs with a list of neurological specialists and units around the country."