MELBOURNE The top seeded Scottish professional tennis player Andy Murray was knocked out of the Australian Open in the fourth round on Sunday by losing 7-5 5-7 6-2 6-4 to German world number 50 Mischa Zverev on Rod Laver Arena. Murray´s defeat follows that of reigning champion Novak Djokovic, who fell to Denis Istomin in the second round on Thursday, leaving the men´s draw at the year´s first grand slam without its top two seeds at the quarter-final stage.