MELBOURNE, Australia — 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. Yet they've never been able to talk shop and freely trade all sorts of thoughts — about tennis and otherwise — until now.

Novak Djokovic's former rival-turned-coach Andy Murray does not want the Serbian to suppress his emotions on court and is even willing to be the target of any angry outbursts as long as the 24-times major winner gives his all at the Australian Open.