Nick Kyrgios forgot how important family was as his life spiralled into chaos, but sibling Christos told Australian media Sunday he has finally "got my baby brother back".

In an emotional tribute penned ahead of the divisive star's Wimbledon final against Novak Djokovic, Christos revealed the pair were recently estranged.

"For a big chunk of the last six or seven years, I lost my little brother. That kid I grew up with, who was so carefree and engaging, was almost gone," he wrote in the Sydney Morning Herald.

"The world changed him. Tennis changed him. He became distracted; always worried about something. Even when you were with him, he wasn't present in the moment."

The richly talented but deeply controversial 27-year-old has long been a polarising figure, with his on-court tantrums resulting in countless fines since bursting on the scene in 2014.

Kyrgios has been fined a total of $14,000 at this year's Wimbledon for his antics, which included spitting towards fans. He also has a looming court appearance in Australia, related to an allegation of assault.

Earlier this year, Kyrgios admitted it all got too much, having suicidal thoughts, abusing drugs and self-harming during a dark period in his life in 2019.

He blamed his depression on the relentless grind of the tennis tour, being away from family and putting pressure on himself.

"He was a prisoner in his own body, going through the motions without any sense of happiness in the life he'd worked so hard to make for himself," said his brother.

"I'd come over to visit mum and dad's and Nick wouldn't get out of bed before midday. And when he did, he was straight out the door. In four or five days, I'd see him for an hour.

"I missed my brother. I didn't know this other person that he had become."

He pinpointed the turning point to Kyrgios meeting current girlfriend Costeen Hatzi late last year, with the player crediting her with helping him switch off after big matches and to separate tennis and life.

"She's helped open his eyes again. She's cut from that same cloth where family is the most important thing," said Christos.

"There was a lot of chaos in Nick's life before he met her. The way he wanted his life to be was not the way things were unfolding.

"Seeing him mature and evolve back into the happy fulfilled version of himself is all that I could have asked for. For us, we've already got our baby brother back. Mum and Dad have got their son back."