The death of New Zealand great Jonah Lomu aged 40 is a "devastating loss", says former Wales captain Jonathan Davies.
Lomu scored 37 tries in 63 matches for New Zealand between 1994 and 2002, but his career was cut short by a rare and serious kidney condition.
Davies was with ex-Cardiff Blues wing Lomu in Dubai recently and described him as one of the game's greatest.
"He changed the way the game was played as a back," he said.
Family spokesman John Mayhew said Lomu passed away at his Auckland home, having returned from a trip to Britain for the World Cup.
The son of Tongan immigrants, he was diagnosed with the rare kidney disorder nephrotic syndrome in 1996, which eventually forced him out of the international scene in 2002 at the age of 27.
He had a kidney transplant in 2004, but the organ stopped functioning in 2011.
But he made 10 appearances for Cardiff Blues between 2005 and 2006, shortly before his retirement from the sport.
'He had such a massive impact'
However, it was at the 1995 Rugby World Cup in South Africa where Lomu came to prominence.
His performance in that tournament has been widely credited with helping attract the major commercial deals that enabled the sport to enter the professional era.
"They'd never seen the likes of him before and he brought new supporters to the game of rugby because they'd never experienced such an athlete on the field," Davies said.
"What he achieved on the field was absolutely incredible and he had such a massive impact on the game of rugby.
"I'm absolutely devastated. It's such a tragic loss at such a young age."
Cardiff Blues, for whom Lomu had a brief spell during the 2005-06 season, said a tribute would take place prior to the European Rugby Challenge Cup game against Harlequins on Thursday.
"On the field he was a game changer, a destructive and supremely talented winger who has given us so many memories that all rugby fans will always cherish," Blues said in a statement.
"Away from the action he was a kind, humble and caring family man who made many friends during his time with us.
"Jonah was loved by his many fans both in our region and around the world. Our heartfelt sympathies go out to Jonah's family and friends at this time."
'A wonderful ambassador'
Welsh Rugby Union chairman Gareth Davies said Wales and the wider rugby world mourned the loss of Lomu.
"He was a great player and a humble and courteous human being who remained a wonderful ambassador for our sport throughout his life," the former Wales fly-half said.
"He will be remembered primarily as a legendary All Black but his links with Wales included a period as a Cardiff Blue and he enjoyed many visits here, through which he maintained strong friendships at all levels of the game.
"Our thoughts are with his family and close friends at this difficult time."
'An absolute phenomenon'
Wales and British and Irish Lions rugby legend and Cardiff Blues board member Sir Gareth Edwards said Lomu was a "great man and a great player".
"He was an absolute phenomenon at the time and indeed has been a great ambassador to the sport and a lovely gentleman," Edwards told BBC Radio Wales' Good Morning Wales.
"I've enjoyed his company over the years and been fortunate to get to know him.
"We had him for 10 games at the Cardiff Blues and he was quite outstanding. He always had time for the children in hospital even though he had problems himself.
"Even though he was only there for a short period of time, he gave everything and had a huge impact on the Blues and the younger members of the team."
'The perfect gentleman'
Lomu's former manager, Welshman Phil Kingsley Jones, said he was "shattered by his passing".
"Jonah was a big part of my family and we are all shattered by his passing," said Jones, father of Newport Gwent Dragons head coach Kingsley Jones.
"I have seen him grow from the young man he was, to the perfect gentleman he had become.
"We had exciting times together and I will treasure his memory always. The world will will be poorer without him.
"My thoughts and love go out to his beautiful family, to his wife Nadene and their sons Brayley and Dhyreille and his Mother Hepi and the Lomu family. "
There will be a special edition of Radio Wales Sport on Jonah Lomu on Wednesday evening from 19:00 GMT