Canada captain Jamie Cudmore has revealed that he was forced to the brink of retirement due to concussion.
During the summer Cudmore had to endure a complete three-month lay-off from sport.
Mood swings, headaches and insomnia meant that the Clermot Auvergne lock considered quitting the game.
But a rapid improvement in his health means that he has shelved all plans of retirement and will lead Canada out in their opening Rugby World Cup game against Ireland.
"I had three months off. I went through all the protocols and all the tests, the neurological work-ups and stuff," he said.
"It was very scary - the whole month of June I was sitting on my couch, I couldn't watch TV, couldn't really do anything.
"I was stuck between the World Cup and retirement.
"I had all kinds of symptoms: headaches, being very irritable, tired when you shouldn't be tired, then being really tired and not being able to sleep.
"That was really bizarre, just lying down and closing your eyes and not being able to sleep.
"It was tough, but thankfully with rest and the right medical help I'm out the other side."
Ireland open their Group D campaign against Canada on Saturday, September 19 with the match in Cardiff’s Millennium Stadium kicking off at 2.30.
