Novak Djokovic shocked the tennis world when he hired former rival and longtime friend Andy Murray to be his coach for the Australian Open just months after Murray retired from the sport.There have been theories thrown out there as to why Djokovic made his coaching decision,

All eyes will be on Andy Murray and Novak Djokovic over the next fortnight at the Australian Open as the Scot sets his former rival a new challenge, having crowned him tennis' 'GOAT'

Novak Djokovic and Andy Murray have known each other for a quarter of a century. They played from the age of 12, meeting 36 times as professionals, including 10 Grand Slam matches.