The catalyst for changing his diet was a consultation with the leading Serbian nutritionist Dr Igor Cetojevic who told Djokovic to stretch out his right arm while holding a slice of bread in his left hand and asked him to resist. The right arm went weak. This confirmed that Djokovic was sensitive to bread and further tests confirmed it was specifically gluten, a protein that is found in wheat and other bread grains. This was the moment he discovered why he had suffered so many mid match performance collapses in his career to date. This was the start of a lifestyle change that led to a gluten-free and no-dairy diet that transformed the Serb to becoming world No 1 within the next 12 months. He was open about this in his book 'Serve to Win' and many professional athletes have had similiar tests and made changes since, although not all of them so open about it.
Dr Igo Cetojevic who had no specialist interest in tennis accidentally whilst flicking channels watched Djokovic's quarter final match with Jo-Wilfried Tsonga at the 2010 Australian Open. Djokovic was two sets to one up when he suffered a health crisis where he had trouble breathing and vomited violently during a toilet break, his strength sapped he won only four more games and lost to Tsonga. Cetojevic suspected immediately he might have an intolerance as the symptoms suggested an inbalance in his digestive system which was triggering an accumulation of toxins in his intestines, in TFT we call this the 'Barrel Effect' based on the work of Dr Doris Rapp, a specialist in sensitivites and allergies. Six months later Cetojevic told Djokovic of his suspicions that food sensitivities were causing his physical problemsand affecting his mental state and the test confirmed it. The diet was changed and the rest is history.