Leukaemia was my toughest opponent

Diagnosed with acute leukaemia in March 2012, Petrov retired from football in May 2013 and after spells as Villa youth coach in 2013, assistant coach in 2015, he would resume full-time training with the first team squad ahead of the 2016/17 season.

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"Leukaemia was probably the toughest of my own opponents," he says. “It was something that I had to battle really hard.

“It was three years of a difficult battle, highs and lows, dark moments, mental issues. But you know what, it just shows you how strong we are as human beings and it's something that I will always remember, I'll never forget.

“I was fortunate to have a great family, a great, great wife, Paulina, she kind of put her life aside to make sure that she looked after me.

“And that's why I have a foundation, based in Bulgaria, England and Spain, I always like to help because I know how important the support is and helping others makes a huge difference.

“We support over 50 hospitals around the world. We create events, we raise funds, and we donate money for other people to have a better treatment and better life.”

That 2016/17 pre-season tour with the Villans saw Petrov score in an 8-0 win over Austrian team GAK, but he was not offered a contract by then-boss Roberto De Matteo.

Yet still, Petrov had come a long way since arriving at Celtic as a teenager in 1999.

“Obviously the start was tough for me, I'd a new coach, the speed of the football as well made it even more difficult,” explains the former Bulgaria international.

“But mainly, I felt that not being able to communicate with my teammates pushed me further from the dressing-room, so it was making sure that I understand what's happening in the dressing-room and I felt that I had to find a solution.

“And my solution at that time was I had a friend who was Scottish, he owned the burger van and obviously noticed that I couldn't speak English, I couldn't explain things — I couldn't place an order.

“We started with basic things and, I'll never regret it because that gave me a chance to stay at Celtic and be successful.”