Young West Ham striker Dylan Tombides has died following a three-year battle with testicular cancer.
The 20-year-old Australian, who made his Hammers first-team debut two years ago, passed away on Friday with his family at his bedside.
West Ham confirmed the news of Tombides' death in a statement on their website.
Tombides was first diagnosed with cancer while representing Australia during the 2011 Under-17 World Cup in Mexico.
"West Ham United announce the sad news that forward Dylan Tombides has passed away at the age of 20 following his brave battle with cancer," the club statement read.
"Dylan passed away on Friday morning with his family by his side having courageously fought the disease for three years after initially being diagnosed with testicular cancer in summer 2011."
Perth-born Tombides was regarded as one of the most exciting young players to come out of Australia after signing with West Ham as a 14-year-old.
After being diagnosed he battled back to make his first-team debut off the substitutes' bench in a League Cup match against Wigan in 2012.
His death will be marked by a minute's applause before West Ham's home match against Crystal Palace this weekend.
West Ham added in the club statement: "Dylan's amazing resilience and positivity saw him through months of surgery and chemotherapy, while his outstanding talent saw him make his first-team debut in a League Cup tie with Wigan Athletic at the Boleyn Ground in September 2012.
"Away from the pitch, Dylan did a huge amount of work to raise awareness of male cancer, supporting the One for the Boys campaign at a number of high-profile events alongside the likes of Hollywood star Samuel L Jackson, snooker star Jimmy White and fellow Australian Peter Andre.
"Dylan was respected by everyone who knew him for his intelligent views on the game and his larger than life character. He was a loving son, amazing brother and well-respected member of the West Ham squad. He will be hugely missed by everyone who had the honour of knowing him.
"His passing will be marked by a minute's applause ahead of Saturday's Barclays Premier League fixture with Crystal Palace at the Boleyn Ground. The Hammers' players will also wear black armbands in his memory.
"The thoughts of everyone associated with the club are with his parents Tracylee and Jim, brother Taylor, his family and friends at this sad time.
"The club request that their privacy is now respected and they are allowed to grieve their much loved son and brother in peace."