World Cup winner Joost van der Westhuizen has died after a long battle with motor neurone disease at the age of 45.
The former South Africa scrum-half was diagnosed with the condition in 2011 and was admitted to a Johannesburg hospital on Saturday morning.
A statement from his charity the J9 Foundation confirmed Van der Westhuizen's death today.
"It is with great sadness that we confirm the passing of Joost," read the short statement, released on Facebook.
"He passed away in his home surrounded by his loved ones. He will be sorely missed."
Van der Westhuizen became one of rugby's greatest scrum-halves in a 10-year Springboks career which began in 1993 and spanned 89 caps.
The gritty competitor racked up 38 tries for South Africa and helped his nation lift the 1995 Rugby World Cup on home soil.
Van der Westhuizen had set up the J9 Foundation to aid others suffering motor neurone disease.
Former Ireland star Brian O'Driscoll was among the first to offer condolences on social media, tweeting: "RIP Joost van der Westhuizen. An incredible player and fighter to the end. The first of the new age 9's".
Statements from his J9 Foundation on Saturday evening and yesterday morning revealed Van der Westhuizen had been in a "critical but stable" condition in an intensive care unit.
Sunday morning's update, though, added that he was "putting up an incredible fight" - and there was further encouragement later in the day.
A statement released around 5pm Irish time yesterday on the J9 Foundation's Facebook page read: "Joost has been much better today however he is tired and been resting this afternoon.
"Thank you for the continued support for him and his family."
Van der Westhuizen starred in the Springboks' 15-12 World Cup final win over New Zealand in 1995, the victory that helped usher in an era of change for South Africa as a nation.
The scrum-half has remained famed ever since for a pivotal tackle on giant All Blacks wing Jonah Lomu - but even in reminiscing in 2013 he quickly downplayed his role.
Van der Westhuizen self-deprecatingly chose instead to highlight being caught out by the Matt Dawson dummy as the British and Irish Lions claimed a series victory in South Africa in 1997.
"Everyone still talks to me about that tackle on Jonah Lomu in the 1995 World Cup final, but every time people mention it, I have to remind them about how I fell for Matt Dawson's dummy in 1997," he told the BBC.