The midfielder released a statement on Aston Villa's official website asking for privacy but adding that a recent picture of Muamba sitting up in hospital could inspire him in his battle with the illness.
"I would like to thank all of the people who have left messages of support - the response has been overwhelming and I appreciate it very much," said Petrov.
"This is a difficult time for my family and myself and I ask people to respect our privacy.
"With the help and love of my family, my teammates, all of my friends in football, Aston Villa Football Club and all of the fans, I am sure I will beat this illness and I am determined to do this.
"I saw the picture released yesterday by Fabrice Muamba, my fellow player, and it has inspired me, as has all of the support in the past 24 hours.
"For me, football will have to take a back seat for a while, but I'm here to support my teammates today and I will continue to support them, as I know they will support me.
"Thank you to everybody."
Earlier, Petrov had told Bulgarian media that "football is over" but vowed to fight for his life.
The 32-year-old midfielder was quoted by Bulgarian sports daily Tema Sport as saying: "I am now beginning to fight for my life and I will fight. Football is over, this is the end."
Petrov said he had felt a strange headache during the first half of Aston Villa's defeat against Arsenal. What at first seemed to be a fever was later diagnosed as acute leukaemia.
"I lost my energy early in the second half and it was very unusual for me," Petrov said.
"But this is life, you see we drank a coffee in London a week ago and now we're talking about things like this."
Petrov received a standing ovation from the crowd at Villa Park ahead of Aston Villa's match with Chelsea with both sets of players also wearing T-shirt bearing support.
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