Novak Djokovic sees off Medvedev to set up Nishikori battle at Australian Open

• Djokovic into last eight with 6-4, 6-7, 6-2, 6-3 win • Nishikori beats Carreño Busta, Raonic defeats Zverev If the guard is changing at the summit of tennis, it is doing so slowly and without conviction, as Novak Djokovic steps into the void left by the departure of Roger Federer. After eight days of the fortnight, the world No 1 is again instilling fear into his side of the draw, as he lurks - fit, seasoned and determined - three matches away from a record seventh Australian Open title. ...