Former Australia lock Dan Vickerman has died at the age of 37, the Australian Rugby Union has confirmed.
South Africa-born Vickerman played 63 Tests for the Wallabies after his debut in 2002 and featured in three World Cups.
"The rugby world is in shock after news of the tragic passing of Dan Vickerman. He was an enforcer on the field and a much-loved character off the field," said ARU chief executive Bill Pulver.
Vickerman moved to Australia from his native South Africa in 2001, joining the Brumbies, and he went on to spend five seasons with the Waratahs.
He also spent the 2009-10 season in England with Premiership side Northampton Saints while studying at Cambridge University.
During that time, Vickerman played in two Varsity matches and also had a short stint with Northampton.
He returned to Australia to continue his career with the Waratahs and also forced his way back into Australia's side, securing a place in their 2011 World Cup party.
Vickerman made his final international appearance in the semi-final of that tournament and was forced to retire in 2012 after persistent problems with stress fractures in his right leg.
The former Wallaby died at his family home in Sydney and is survived by wife Sarah and two sons.
No details of the cause of death have been disclosed.