Seven-time Wimbledon champion Novak Djokovic is concerned about the danger posed by surging Australian Alexei Popyrin as he seeks to regain his crown.
The 24-time grand slam winner, who still sounds not entirely happy about his form as he recovers from knee surgery four weeks ago, believes the lanky Sydneysider is becoming a complete player.
The pair played at the Australian Open in January when Djokovic prevailed in four sets, but only after the big-serving Popyrin had held set points for a 2-1 lead.
