Tennis icon Bjorn Borg has opened up on his cancer diagnosis, startling drug use and near-death collapse.

The enigmatic Swede, 69, who won 11 grand slams and five consecutive Wimbledon titles, has kept his life private until now.

He is releasing a bombshell memoir - 'Heartbeats' - which contains extraordinary revelations about his wild partying and 'extremely aggressive' prostate cancer diagnosis.

Borg had an operation last year and is in remission. He describes himself as 'living day by day and year by year' and admits he finds the diagnosis 'difficult psychologically'.

'I spoke to the doctor and he said this is really, really bad,' Borg told BBC Breakfast.

'He said you have these sleeping cancer cells [and] it's going to be a fight in the future.

Borg plays a shot during the 1976 US Open - the legendary tennis player, now 69, has been diagnosed with aggressive prostate cancer

Borg, pictured here in 1980 with his first wife Mariana Simionescu, has opened up about his wild years of partying in his bombshell new memoir

'Every six months I go and test myself. I did my last test two weeks ago. It's a thing I have to live with.'

In the final chapter of his memoir, which will be released in the UK and USA next week, Borg says the cancer is 'at it's most advanced stage' and is treating is as though he is 'playing a Wimbledon final'.

Borg was a global superstar and the biggest name in tennis until he abruptly quit the sport in his prime aged 25.

'All I could think about was how miserable my life had become', he says about calling time on his career having lost to John McEnroe in the Wimbledon and US Open finals.

From there, his life spiralled out of control. In the book, he says: 'The first time I tried cocaine (the year after retirement in 1982) I got the same kind of rush I used to get from tennis.'

He also describes the moment he collapsed on a bridge in the Netherlands, going into cardiac arrest and requiring resuscitation.

He writes: 'I feel the ground beneath my feet heaving. It's like I'm moving in the air; I can't move forward. We have to cross a bridge, a typical Dutch bridge over a canal where houseboats are swaying.

'At that moment, I sink to the ground. Everything goes black, and the unimaginable happens. I'm dying. I see no bright light or a film of my life passing by; everything is simply gone.

Borg was seen at Wimbledon earlier this year where he won five grand slams in a row

Borg is pictured with Chevy Chase at Caesars Palace in Las Vegas in 1982

'My heart no longer goes boom boom boom, because now it's standing still. Yet, just before everything goes black, I think: how could it have come to this?'

The evening had begun with a lowkey dinner but soon descended into a lethal cocktail of drink and drugs.

The party was in the midst of an exhibition tournament and Borg said: 'I ran into people I knew from outside the tennis world. One thing led to another. Drugs, alcohol, and pills were added.

'After a very short night, I walked to the tennis park with my father. I said, "I feel so bad, I can't play." He replied that it would be fine. And then, bang, I collapsed.'

Borg reflects that the 'worst shame of it all' was waking up in the hospital bed to see his father beside him.

It was a lost decade for Borg, who also had to have his stomach pumped in 1989 when he couldn't be woken up.

He denies that it was a suicide attempt and simply put it down to being a 'wild night' in Italy.

Borg is pictured in Monaco in 1983 having called time on his tennis career

'Once I had the drugs in my sights, I was at their mercy for the rest of the evening,' he writes. 'I couldn't stop myself.'

Borg managed to stop the drink and drugs with the help of his third wife, Patricia Östfeld and now has a strong relationship with his two sons.

The sporting superstar was recently asked why after so many years of treasured privacy, he has decided to tell all.

He replied that it is important to him 'to have a good beginning and a good ending'.

Tennis legend Bjorn Bjorg reveals secret cardiac arrest