You could be forgiven for missing Vinod Kambli's announcement last month that he was retiring from first-class cricket. After all, the 39-year-old Indian batsman hadn't played a first-class game in six years, or an international one in 11. But, if things had gone slightly differently, we could currently be celebrating the retirement of one of the greatest players of all time. His tale shows how thin the line is between success and failure, and it also shows where that line is located: in the head.

A 17-year-old Kambli etched...