Six-time grand slam singles champion Becker was sentenced to two and a half years in jail in April after being found guilty of hiding £2.5million worth of assets and loans to avoid paying debts when he was declared bankrupt in 2017.

The German reportedly spent the first few weeks of his sentence at Wandsworth Prison in London before being moved to the low-security Huntercombe prison in Oxfordshire in May.

The 55-year-old served just eight months of his sentence before being allowed out and has returned to his homeland, with reports he is not allowed back in the United Kingdom for a decade.

In an interview with Sat.1 that was broadcast on Tuesday, the tennis legend has opened up on the dark days he has experienced but says he has learned a "very expensive" lesson.

"In prison you are a nobody, you are only a number. Mine was A2923EV," he recalled when breaking his silence. "I wasn't called Boris, I was a number. And nobody gives a s*** who you are.

"When the cell door closes, the whole world collapses. This is the loneliest moment I've ever had. 

"There is only you with your thoughts. There's a carousel in your head, of course. You try to breathe calmly. I was afraid, I didn't cry.

"I believe I rediscovered the human in me, the person I once was. I've learned a hard lesson. A very expensive one. A very painful one. 

"But the whole thing has taught me something very important and worthwhile. And some things happen for a good reason."

Recalling the day of his release, Becker, who lived in London before he was sent to prison, said: "From six o'clock that morning I sat on the edge of my bed, and hoped that the cell door would open. 

"They came to get me at 7.30am, unlocked the door and asked: 'Are you ready?' I said: 'Let’s go!' I had already packed everything beforehand."