In his long career he has represented the New Zealand Kiwis within rugby league and New Zealand Māori sides and has played for the Leeds Rhinos, Bradford Northern, Warrington Wolves, Castleford Tigers and Halifax [REF].
Gary Mercer played , i.e. number 3, in Warrington's 14-36 defeat by Wigan in the 1990 Challenge Cup Final during the 1989-90 season at Wembley Stadium, London on Saturday 28 April 1990, in front of a crowd of 77,729 [REF].