A Canterbury junior, Sponberg made his debut for Western Suburbs in Round 6 of the 1932 season.
However, as minor premiers, Souths were allowed right of challenge, and so a rematch of the grand final was played a week later.
[3] Sponberg played lock in the 1934 Grand Final, with his team defeating Eastern Suburbs 15-12.
[8] Sponberg died at his home on the Central Coast of New South Wales following a short illness on 17 June 2000, aged 87.
In 2004, Sponberg was named in the Canterbury 70th year Berries to Bulldogs Team Of Champions as lock forward.
This rugby league football biography relating to an Australian born in the 1910s is a stub.