Former Wallabies lock Dan Vickerman has passed away suddenly at the age of 37, plunging the rugby world into a state of shock, the Australian Rugby Union said Sunday.
The South African-born lock, who played 63 Tests for the Wallabies up until 2011, passed away at his family home in Sydney late Saturday, the ARU said in a statement.
Vickerman leaves behind wife Sarah and two sons. Authorities have yet to comment on the cause of death.
"The rugby world is in shock today after news of the tragic passing of Dan Vickerman," ARU chief executive Bill Pulver said.
"Dan was an uncompromising competitor who forged a wonderful international rugby career despite a number of injury setbacks along the way.
"A much-loved character off the field. He cared deeply about the game and the players, helping players transition into life after rugby in his role with (the players association) RUPA following his retirement.
"Our thoughts and prayers are with Dan's family at this extremely difficult time."
Former Wallaby Phil Waugh, a close friend and teammate, said it was a terrible day for rugby in Australia.
"We all have huge admiration for the guy that he was," Waugh said. "He's a guy that necessarily wasn't the loudest in the team, but had the most respect from everyone playing with him. There's so many positive memories of him on and off the field."
Another former Wallabies teammate Matt Burke added: "Very abrasive as a player but a great lad, great tourist, a very good player and was just one of the good lads that you enjoyed his company."
Springbok great Victor Matfield tweeted: "Waking up to sad news about Dan Vickerman this morning. Always enjoyed playing against him. A real competitor and a great guy."
RUPA CEO Ross Xenos said Vickerman was well respected in the rugby world.
"Dan was universally respected by his peers and the rugby community during and beyond his playing days. Since retiring, he was very generous in giving back to the game through coaching and voluntary roles supporting players' off-field development," Xenos said.
"We encourage all players who are affected by today's terribly sad news to support and be there for each other and to contact RUPA if they would like to talk."
Born in Cape Town, Vickerman moved to Australia and the Brumbies in the 2001 season.
The following year he made his Test debut in a 31-25 Wallabies victory over France in Sydney.
Following three seasons with the Brumbies, Vickerman joined the Waratahs in 2004 where he played five seasons in Sydney.
After playing in his second Rugby World Cup in 2007 in France, he quit international rugby for three years to study in England and earned a degree in Land Economics from Cambridge University.
While in England he played in two Varsity matches and also had a short stint with the Northampton Saints in the 2009-10 season.
The towering backrower returned to Australia to continue his career with the Waratahs and Wallabies, earning a place in the Wallabies 2011 Rugby World Cup squad.
Vickerman made his final Test appearance in the 2011 World Cup semi-final against New Zealand in Auckland.
He was forced to retire in 2012 through persistent problems with stress fractures in his right leg.
After retiring Vickerman worked in the real estate and development industry and was helping at Sydney University Rugby club until last year.