One of the first features you notice about Luke Brattan are his piercing blue eyes. They beam like headlights, lighting up when he laughs and match the bright shade of his sky blue Sydney FC jersey. However, it isn't long before they reveal the pain that lies beneath.

Despite what his and his team's performances might suggest, this season has one of anguish for the 29-year-old. Hours before he was to play Adelaide United in the opening game of the season, Brattan learned his younger sister Holli-Mia had cancer. Two months later, his mother Mandi was diagnosed with the disease as well.

Luke Brattan with his sister Holli-Mia. Supplied

"I was just in shock," Brattan said. "I have never had anything like this happen, being so close to them makes it very tough. Now I struggle to get through games."

The midfielder might appear to be in near-career best form with the high-flying league leaders but Brattan says there have been plenty of moments he hasn't been switched on during games. Instead, his mind has drifted to thoughts about Holli-Mia who, at the age of 22, is undergoing chemotherapy and is preparing for a bone-marrow transplant.

"It has been hard. There have been times in games where I feel I am not in the game which is not great," he said. "Especially when I finish training and I find out she [Holli-Mia] has had a rough day. It’s hard to think about football and it puts things into perspective."

"She has been through hell everyday... She is incredible, she is definitely my hero. She has done an incredible job so far." Sydney FC midfielder Luke Brattan.

When the schedule allows, Sydney FC have given Brattan extra time to travel to Brisbane to be by the his sister's side - she has spent the better part of the past four months in hospital.

Sydney FC midfielder Luke Brattan has been travelling back to Brisbane throughout the season to be with his sister. Nick Moir

"She has been through hell everyday. Now she had chemo, she takes her backpack and takes the chemo home," he said. "It’s full on and now it’s just part of everyday life [from] now until its finished. She is incredible, she is definitely my hero. She has done an incredible job so far."

Brattan's mother is on the mend after surgery and now the family is doing whatever they can to help Holli-Mia. Brattan's older brother will be the bone marrow donor having been identified as a match while the Sydney FC midfielder will be using his public profile to raise awareness and funds to help battle the disease.

Other than those bright blue eyes, Brattan is perhaps most distinguishable for his long blonde locks. But in a matter of weeks though they will be gone. Brattan will take part in the Leukaemia Foundation's World's Greatest Shave to raise awareness and funds for research into blood cancers.

"I want everyone to know that if it happens to them, the Leukaemia Foundation is an incredible foundation, they have helped my sister incredibly. If it happens to them or someone close to them, they have someone to turn to," he said. "We are in life together, nobody is ever alone."