J-League first-division heavyweights Yokohama F Marinos are set to appoint former Australia international Harry Kewell as their new manager, a source with knowledge of the matter said Saturday. The 45-year-old Kewell has been an assistant manager to Brendan Rodgers at Celtic in the Scottish Premiership this season. He will take the reins at Nissan Stadium from countryman Kevin Muscat, who steered Marinos to the 2022 J-League title and departed after a second-place finish this year. Kewell remains one of the biggest names in Australian football following a distinguished playing career as an att…