He has been battling the condition for seven years. 

He is regarded as one of the greatest ever scrum-halves and helped South Africa claim the 1995 World Cup.

He was admitted to a Johannesburg hospital on Saturday. 

His J9 Foundation, which helps fellow MND sufferers, released a statement on Sunday stating:

"Joost remains in ICU in a critical but stable condition. He is responding well to his loved ones and putting up an incredible fight. He really is our Superman!"

 

A spokesperson told a South African reporter:

"Joost has been much better today, however he is tired and been resting this afternoon."

His former South Africa teammate Hennie le Roux revealed to South Africa media that he "was being kept alive on machines" and that it "doesn't look good for Joost."

The 45-year-old formerly told the Telegraph:

"I had a choice. Either I stay at home and die, or I live my life," he said. "I have a platform and now I'm using it to help with MND. They [the doctors] are going to tell them they have two to five years [to live] – and that's bull****. You live as long as you want, as long as you are positive. They told me 24 months. I'm now on 50."