Cech was injured Saturday in the opening minute of Chelsea's 1-0 victory at Reading after Stephen Hunt hit the goalkeeper in the head with his knee.

The Blues also lost backup goalkeeper Carlo Cudicini with concussion late in the game and manager Jose Mourinho is set to start Hilario against FC Barcelona in the Champions League on Wednesday.

Cech was still in an Oxford hospital Monday after surgery to repair the fracture. An expert on head injuries said he risked a fatal injury if he were rushed back to action.

``He risks what is known as second impact syndrome,'' said Peter Hamlyn, consultant neurosurgeon and a specialist in sports and exercise medicine at St. Bartholomew's Hospital in London.

``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.''

Hamlyn said Cech needed a long period of rest before he considers returning to competitive soccer.

``I would think Cech is likely to be out for at least six months,'' Hamlyn said. ``That is about the length of time it takes for 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, the Football Association was awaiting the report of match referee Mike Riley, who took no action against Hunt over the incident.

FA rules state that, if the referee sees the incident and takes no action, it can't take any disciplinary action against any of the players involved.

Mourinho was furious with Hunt's challenge, suggesting the Reading player did not try to avoid the collision and seconds later was laughing about the incident in front of the Chelsea bench.

Both Hunt and Reading manager Steve Coppell said the forward did not intend to collide with Cech.

Hunt wrote a letter to the Czech Republic international on Monday wishing him a full recovery.

``I can guarantee that I did not attempt to injure Petr, and I am very upset that the collision has resulted in such a bad injury,'' the Reading forward said.

Cech and Cudicini are regarded as the best pair of goalkeepers at any English Premier League club, but Hilario, who played under Mourinho at FC Porto, has not played a competitive match for the Blues.

Chelsea midfielder Joe Cole said he was confident the Portuguese goalkeeper had the experience to face Barcelona, however.

``He is a very good goalkeeper,'' Cole said. ``If he comes in he won't let anyone down. He looks good in training and is an experienced goalkeeper.''