Former Chelsea star Oscar has been forced to retire from professional football after collapsing in training due to a heart condition. The Brazilian announced this weekend that he had been forced to hang up his boots prematurely because of his health. The 34-year-old was treated in hospital after becoming unwell at what turned out to be his final club, Sao Paulo, while doing physical pre-season testing with the club in November. It was later determined that he was experiencing vasovagal syncope -