Former Rangers player Fernando Ricksen has died at age 43 after a six-year battle with motor neurone disease, the Ibrox club have confirmed.
The Dutch international had been battling the condition since 2013.
Ricksen was a fans' favourite during his six-year spell at Rangers after being signed by Dick Advocaat in 2000.
He helped the club win the domestic cup double in 2002, the treble in 2003 and was captain for a trophy double in 2005.
Rangers said they were "deeply saddened" to be announcing the news of Ricksen's passing.
"The thoughts of everyone at Rangers is today with his wife Veronika, his daughter Isabella and all his family and friends," the club added.
After diagnosis in 2013, Ricksen spent his years battling motor neurone disease campaigning and raising money to find a cure for the debilitating condition, which affects the nerves and causes weakness over time.
His charity has raised over £1m in a bid to help scientists with research. Speaking to ITV News in June, when he used eye movements to talk via a computer, Ricksen urged those in sport to do more to help pressure drugs companies to find a cure.
"The sports world could put more pressure on the pharmaceutical companies," he said. "This disease is not lucrative enough so it has no priority.
"If tomorrow an MND epidemic came we would have a cure within a week. It's disgusting but a reality."
The former Dutch international also opened up about his own battle with the illness.
"Your body doesn't want to anymore but your brain is functioning without problems. You start losing the ability to speak. Then the legs start to get wobbly. Then you can't lift your legs anymore and you start falling.
"Don't give up," was his message to others inflicted with MND.
Ricksen arrived at Rangers from AZ Alkmaar after starting his career at Fortuna Sittard and through his character, attitude, and commitment, quickly became a fans' favourite.
Rangers team-mate Arthur Newman played alongside Ricksen for three years, and says his friend was full of passion on the pitch.
"Straight from the beginning he gave 100% for the jersey, he was a winner," the Dutchman told BBC Scotland.
"He was a favourite of the fans because of what he gave on the park and also as captain of the team he gave 110% for the result.
"I think that's one of the reasons why he came back to Scotland. He wanted to stay there in the hospice, he treasured those really good memories of playing for Rangers.
"He was a strong character. In 2013 he came out with the news that he was suffering from MND and people thought he wouldn't last long.
"But he fought for nearly six years against it and that shows how he is as a person and as a character - never give up, always give 100% and go for it."
Ricksen left Ibrox for Russian side Zenit St Petersburg and was there reunited with Advocaat. He was part of the Zenit squad that reached the 2008 Uefa Cup final against Rangers, though he did not feature as the Russian side won 2-0.
Between 2000 and 2003, Ricksen won 12 caps for his country. Former Scotland striker Billy Dodds also played alongside him at Rangers and shared some fond memories.
"He would cause trouble in an empty house, but he was so genuine and that's what has saddened me," Dodds said. "It's ok talking about him as a player, but there was a good side to Fernando that a lot of people will miss.
"I remember one pre-season we were in Holland, and we had a bus journey and that's when he decided to open up a wee bit. I was sitting next to him and he just told me about his family, his journey and it wasn't easy.
Dodds added: "There was a thinking side to him, there was a bit of bedevilment, he wanted to kick you, but that's because he was a winner. Opposing fans loved to hate him, but he loved that, that made him tick and made him play."