Messages of support have been flooding in for the former Rangers star after he revealed on live television that he is suffering from Amyotrophic Lateral Sclerosis
In a live interview with Dutch television programme 'The World Keeps Turning' the 37-year-old revealed the he is suffering from Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig's disease.
When asked why he was speaking slowly while promoting the release of his new book, a tearful Ricksen replied: "I find it difficult to talk because I've got ALS.
"The medical people have said my condition could worsen quickly. I do not know anymore. I have feared for a couple of months I was in trouble - it is very hard to take.
"Inside me there is a fighting spirit, there always has been. I will fight this - I know it will be difficult but I will battle all the way."
ALS is a debilitating disease causing rapidly progressive weakness and muscle atrophy, with around half of those diagnosed given a life expectancy of less than five years.
Rangers manager Ally McCoist pledged his support on behalf of the Glasgow club to Ricksen, who won seven trophies between 2000 and 2006 at Ibrox.
"This is truly devastating news and the thoughts of everyone associated with Rangers Football Club are with Fernando," McCoist told the club's official website.
"We will of course support Fernando and his family in any way we can and there is no doubt football is put into perspective when you hear news like this.
"I have seen images of Fernando in today's media and my heart goes out to him and his family. I cannot begin to imagine what he is going through at the moment.
"He enjoyed a fantastic career at Rangers, notably captaining Rangers to the title in 2005 at Easter Road, and I know our fans will also show their support for him."
Former Rangers manager Dick Advocaat also sent out a message of support for Ricksen, who he signed from AZ Alkmaar before taking him to Zenit St Petersburg.
Speaking to the Eredivisie side's website, Advocaat said: "I always enjoyed working with Fernando. Of course, the stories about his escapades are known by many, but under me he was always a decent professional, and respectful.
"I have worked in a good and successful way with him at Rangers, Zenit and the Dutch national team. With Zenit, we won the Russian title and the Uefa Cup.
"It's terrible news Fernando is suffering ALS. It has deeply touched me. Also here at AZ, it touched people. He had three successful years here in Alkmaar.
"The club has good memories of him. I want to wish Fernando and his family and friends a lot of strength the coming period. Hopefully his winning spirit will give him the best."
Celtic also issued a statement of their own, which read: "The thoughts of everyone at Celtic are with Fernando Ricksen and his family following the news that he has been diagnosed with Motor Neurone Disease.
"Everyone at Celtic passes on our best wishes to Fernando at this very difficult time."
Celtic legend Jimmy Johnstone died of motor neurone disease at the age of 61 in 2006 following a five-year battle.