Novak Djokovic has long credited a series of unusual methods for helping him become one of the greatest players ever, including his "special relationship" with a Melbourne tree over the past 15 years.

The world No. 1, who swears by a plant-based diet, extols the virtues of meditation and has previously used a spiritual guru, has never been shy on the subject of his eccentricities.

As he targets an unprecedented 11th Australian Open title, he said he had been connecting again with his "old friend" — a Melbourne fig tree in the city's Royal Botanic Gardens that he likes to hug and climb.