Former South Africa captain Joost van der Westhuizen has died at the age of 45 after a battle with motor neurone disease.
A World Cup winner in 1995, the former scrum-half had been living with the disease since 2011.
He was admitted to a Johannesburg hospital on Saturday morning and statements from his J9 Foundation on Saturday evening reported that he was "critical but stable" in an intensive care unit.
An update on Sunday morning said Van der Westhuizen was "putting up an incredible fight".
But on Monday morning J9 confirmed he had passed away, saying: "It is with great sadness that we confirm the passing of Joost. He passed away in his home surrounded by his loved ones. He will be sorely missed."
The J9 foundation was set up by Van der Westhuizen to aid people suffering from MND.
Regarded as one of the greatest scrum-halves in rugby history, Van der Westhuizen won 89 caps for the Springboks between 1993 and 2003, starting the 15-12 World Cup final win over New Zealand in 1995 at Ellis Park. He scored what was then a Springbok record of 38 tries.
Van der Westhuizen was a one-club man, playing his entire career with the Blue Bulls.
The club's CEO Barend van Graan said: "If there's one thing we can learn from Joost it was his passion for life. That we will never forget."