Ferguson remains in intensive care but has responded well to treatment and has been showing positive signs of recovery.
Jones is one of those now at United who was signed by Ferguson, having joined from Blackburn in 2011, and the England worldwide has described how pivotal his old manager was in helping him settle in.
"I was with him on the pitch last week, I went to see him in the box after the game on Sunday".
"He is such a legend in my eyes".
United club captain Michael Carrick said he was "absolutely devastated" by the news, while Mike Phelan, who played under Ferguson for United and later served as his assistant, wished his former boss a swift recovery.
"I never played for him but I played against him many times - an icon all over the world", Defoe told Press Association Sport. Hopefully, he'll recover well.
Current top-flight managers at United's rival clubs such as Arsene Wenger, Pep Guardiola and Jurgen Klopp all had messages of support for 76-year-old Ferguson over the weekend. "He is a strong man and an optimistic man".
"All the Manchester City fans in the stadium, you can not find one person who does not wish the best for an unbelievable person", said City manager Pep Guardiola on the day City lifted the Premier League trophy. "He told me he's doing a lot of exercise, he looked very happy".
"My thoughts and prayers are with you, my dear friend", Real Madrid forward Cristiano Ronaldo wrote on social media accounts in support of his former mentor at Old Trafford.
"I was devastated. I got a text on Saturday evening and I couldn't quite believe it".
Giggs was just one of many youngsters that Ferguson nurtured from the United academy to stardom on the worldwide stage.
'Everyone at the club is wishing him all the best and his family as well.