Novak Djokovic says he withdrew from a public practice match against Daniil Medvedev as he didn’t want to take risks before the Australian Open.The Serbian appeared to tweak his hamstring muscle during the Adelaide International semi-final against Daniil Medvedev last week which required some medical attention.He came through that match and defeated Seb Korda in the final to win the title, but said afterwards that he’d had to go ‘deep into night last night with work done with the physio’ to get the hamstring ready.Djokovic was taking part in an open practice match, once again with Daniil Medvedev on Wednesday on Rod Laver Arena, when he seemed to be still struggling with the hamstri …