Former Celtic striker John Hartson has claimed that Aston Villa captain Stiliyan Petrov was "upbeat" before undergoing treatment in London today.

The Bulgaria international was diagnosed with Acute Leukaemia on Friday and has begun a series of tests with a specialist in the capital today.

Hartson, who defeated cancer in 2009, believes that his former teammate will fight to overcome his battle with the disease.

"He's the kind of lad who wants to take this head on," Hartson told BBC Scotland. "He's very strong. His fitness, I'm sure, will help him. He knows he has so much support from throughout football.

"A lot of it is psychological. You have to get your head around what is happening and dealing with it as openly as you can. You do know there is a lot of support out there when you are battling a near death experience like I went through.

"Stiliyan knows he has support from his peers and his family, which will be very important for him."

The 32-year-old midfielder has been at Aston Villa since 2006.