The 23-year-old was on trial for Ryman Premier League side Tonbridge Angels when he fell unconscious in the second half of a pre-season friendly against Whyteleafe FC in Surrey last night.
The incident happened 20 minutes into the second half of the match, causing the game to be abandoned.
Two physios ran onto the pitch to try to resuscitate the footballer, were they were quickly joined by emergency paramedics.
However Junior Dian’s life could not be saved.
The young footballer tragically passed away at St George’s Hospital in the early hours of Wednesday morning.
“This is devastating news and our only crumb of comfort is that Junior lost his life doing something he obviously enjoyed so much," said Tonbridge chairman Steve Churcher in a statement on the club’s website.
"All our thoughts and sympathies are with his family.”
He added: “Also I would like to thank everyone at Whyteleafe FC for their support and professionalism during this very distressing incident yesterday evening.".
Harry Redknapp was amongst those on Twitter who paid tribute to Junior Dian.
He wrote: “Terrible news about Junior Dian who died playing football. Sending my thoughts to his family.”
One of Junior’s close friends also took to Twitter to remember the rising star.
He wrote: “This just goes to show that life is no joke and we can't take this for granted. Live everyday to the fullest and appreciate everything, ‘cause you can be here and the next [day] you could be gone.
“Let me break it down. 7:30 in the warm up he was telling me how he wants to bad it up. And I told him he would if he plays his normal game.
“9:20pm he collapsed. Like that's the realness of it.”
Our thoughts are with Junior Dian’s family and friends at this tragic time.