Ferdinand was making the journey from Manchester to London in the same carriage as commuter Michelle Clarke, who, amazed, texted friends to tell them she was in the presence of the former England captain.
One of those friends, Laura Wilson, runs a charity called Dance Aid, which uses dance to help transform the lives of vulnerable children, and spotted an opportunity to make a cheeky request of Ferdinand, as he sat in the carriage completely unaware of the plot being hatched.
Laura tweeted: "Hey Rio any chance u might b on a train southward from Manc?! 1 of our ambassadors has spotted u! In fact she's sitting opposite!"
Incredibly, Ferdinand saw the tweet, broke off from what he was doing and started quizzing a stunned Michelle all about Dance Aid and how he could get involved and help raise awareness for the charity.
When Michelle reported back that Ferdinand had not only noticed the tweet, but also engaged her in conversation about the charity, Laura was shocked. "We both screamed at each other!" she says, taking up the story in an interview with Yahoo!-Eurosport.
"Michelle had texted a few mates to tell them she was sitting opposite Rio Ferdinand. Some were texting back to ask for a photo, the Liverpool fans were saying, 'Trip him over', that sort of thing. But I said, 'You are not getting off that train until you have spoken to him about Dance Aid.
"She said she would never have the balls to do that, so I tweeted him to tell him an ambassador of the charity was sat opposite him. I texted her to tell her and she was going completely crazy.
"Then he initiated the conversation and she was completely flabbergasted. I think both of us thought that it was just a tweet and he wouldn't do anything, and we were utterly amazed when he did.
"He has asked me if I could email him information about the charity and about how he can get involved, and he has been very enthusiastic about it from the get-go, presumably thanks to whatever Michelle told him."
Dance Aid says its aim is to fundraise through dance to "provide support, protection, and opportunity to thousands of vulnerable children", and funds projects all over the globe, tackling issues such as the proliferation of AIDS in sub-Saharan Africa, street poverty in the Philippines and child welfare in the UK.
Laura says Ferdinand's selfless act could have an unimaginable impact on the charity, and the causes it promotes.
"It could be absolutely huge," she says. "Dance Aid fundraises primarily through dance to transform the lives of orphans and poor and disabled children. As a result of the work we do, most of the endorsements we get from celebrities are from the dance world - the likes of Flawless and Diversity, people like that.
"Rio is a more universally known celebrity and it is huge. For any charity it is all about awareness, which then facilitates fundraising, so his endorsement could be absolutely the biggest thing that has happened to the charity in its history."
For more information on Dance Aid, and the excellent work the charity does in improving the lives of vulnerable children across the world, visit danceaid.org.
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