Wales international Lloyd Burns is facing the possibility of heart surgery after being forced to retire from rugby.
The 27-year-old Newport Gwent Dragons forward was a World Cup squad member in New Zealand last autumn and won seven caps, four of them during that tournament, but has been sidelined since January due to a neck injury that forced him out of this season's triumphant RBS 6 Nations Championship.
The Dragons have now revealed that "ongoing tests" from the neck problem have shown aorta damage, resulting in immediate retirement, with possible heart surgery to follow.
Dragons rugby director Robert Beale said: "Everything Lloyd has achieved in life he has earned through hard work and dedication.
"His enforced retirement from the game has come as a massive shock to Lloyd and his family and will resonate throughout the rugby world.
"I am personally relieved that this serious condition has been identified off the field of play. I would therefore like to thank our medical team at the Dragons, staff at the Royal Gwent Hospital in Newport and University of Wales, Cardiff for all their efforts in ensuring Lloyd has, and will continue to receive, the highest standards of care."
Some of Burns's Wales colleagues paid tribute to him on Twitter, including captain Sam Warburton who said: "Terrible news, great player and guy, hope recovery goes well."
Centre Jamie Roberts, who is himself currently recovering from knee surgery, tweeted: "Sad news about Lloyd Burns' retirement from rugby....great player, good bloke....here's to a speedy recovery."
And Burns's Wales and Dragons team-mate Dan Lydiate tweeted: "Absolutely gutted for my mate Lloyd Burns forced to retire, top player but more importantly top bloke."
Wales full-back Leigh Halfpenny, meanwhile, said: "Absolutely gutted to hear the sad news Lloyd Burns forced to retire. Great player and a fantastic bloke."