Scans revealed a significant injury to the neck and, unfortunately, in the early hours of Monday morning he developed complications which required emergency surgery.
His condition is currently stable but serious. He is under observation in the Intensive Care Unit at the University Hospital of Wales and further tests will be performed over the next 24 hours. Further surgery may be performed in the next 48 hours.
Gareth is receiving support from his family, officials of Neath Rugby and fellow squad members. The club is confident that he has received the best treatment available and fervently hopes that his recovery will proceed as quickly as possible.
Neath Rugby hopes that supporters will respect the privacy of the family at this time. A further statement will be issued as soon as the club has further information.
Press Statement: From the Welsh Rugby Union
WRU Chairman David Pickering said: "The thoughts of us all are with Gareth and his family at this time.
"We are all hoping for positive developments over the days ahead and I know he will be receiving the best medical care possible at the University Hospital of Wales.
"I was present at the game in Cardiff, so I witnessed the incident, and I want to thank everyone involved for the help Gareth received after he suffered this serious injury."