Leukaemia
On 30 March 2012, Petrov was diagnosed with acute leukaemia. The condition was diagnosed following tests after Petrov developed a fever following Aston Villa's 3–0 defeat to Arsenal. Because of this, Petrov told Bulgarian press that he plans to retire from club and international football; his agent later denied any reports of retirement: "It is not true that Stiliyan has said he is retiring from football. What he did say was that he was fighting for his life and that he will fight to recover." He visited Villa Park for the visit of Chelsea and in the 19th minute, the crowd gave him an ovation with applause. Petrov's shirt number was 19, hence the 19th minute. Aston Villa lost the match 2–4. On 10 June Aston Villa manager Paul Lambert announced that Petrov would remain Aston Villa's club captain for the 2012–13 season. In his absence the team captaincy was taken over by Dutch defender Ron Vlaar. On his 33rd birthday, Petrov visited his teammates on the first day of their pre season training, and was presented with a cake by the players, who sang happy birthday to him and gave him a round of applause.
On 2 August 2012, it was announced that Petrov's leukaemia was in remission.
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