Petr Cech believes his trademark helmet might have spared him a second serious head injury almost five years after suffering the skull fracture that convinced him to wear it.
Chelsea goalkeeper Cech needed hospital treatment after being clattered by Orlando Sa during Wednesday night's Carling Cup victory over Fulham.
Cech revealed he could not see straight or stand up in the dressing room at half-time and that, even after being given the all-clear by medics, he was close to pulling out of Saturday's Barclays Premier League win over Swansea.
But it could have been even worse for the 29-year-old had he not been wearing the headgear he has donned in every match since a collision with Reading's Stephen Hunt in October 2006 forced him to have metal plates attached to his skull. Recalling Wednesday night's incident, Cech said: "My head went back like when you get a right hook in boxing."
He added: "What happened, I don't know. I think the helmet took most of the impact."
Cech felt able to continue for the few minutes until half-time but failed to re-emerge after the break as concussion set in.
"When I came inside to the dressing room, I couldn't see properly and I didn't have the awareness of the space," he said. "There was no way I could continue, although I had played for the last two minutes of the half. I thought I would be all right but, as soon as I got into the dressing room, it was clear that my head wasn't working the way it should.
"As soon as I sat down, I couldn't stand up. So we decided not to play because it would have been really stupid for me to carry on."
Cech, who watched team-mate Didier Drogba knocked out cold in a collision last month's win over Norwich, added: "I went to hospital and had a scan. With my history, they were not taking any chances. But all was clear and I was able to train on Friday.
"We weren't sure if I would be able to play (against Swansea). I went out for the warm-up and we said, `If I'm okay in the warm-up then I play. But if I'm not right I'm not going to play.' You can't be naive and stupid to do things you shouldn't.
"It would be stupid for me to play a game if I was not right. If you're not right, you can make a mistake that will cost your team-mates a game. So I had full awareness of what is at stake and I was fine and decided to play."
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