Chelsea goalkeeper Petr Cech is likely to be out of action for at least six months, according to a leading neuro-surgeon.
Cech underwent surgery on Sunday after suffering a depressed fracture of the skull during Saturday's 1-0 win at Reading.
Chelsea's medical staff have so far refused to comment on how long the injury will keep the Czech Republic international on the sidelines for, but Peter Hamlyn, consultant neuro-surgeon and director for the centre of sports and exercise medicine at St Bartholomew's Hospital in London, has warned he faces a lengthy lay-off.
"If Petr Cech returns too soon from his head injury, the result could be fatal," Hamlyn told the Daily Telegraph.
"He risks what is known as 'second impact syndrome'. This happens when a second blow causes swelling to the brain before it has recovered fully from an earlier injury. It is a situation that could prove fatal, even if the first blow is deemed not to be serious.
"With that in mind, I would think Cech is likely to be out for at least six months.
"That is about the length of time it takes for stout bone healing to take place. If the brain underlying the fracture has been greatly injured, his time out may be even longer.
"Luckily for him, skull fractures are not normally associated with severe injuries to the brain, which means we can anticipate Cech making a full recovery."
Meanwhile, Chelsea have confirmed that they plan to write to the Football Association to demand that action is taken against Reading's Stephen Hunt, whose late challenge led to Cech's injury.