He played with Concordia until the establishment of the new regime club Dinamo Zagreb.
Monsider was one of three Concordia players to move to the new club (along with Vinko Golob and Slavko Beda).
He made his debut for the Independent State of Croatia, a World War II-era puppet state of Nazi Germany, in a June 1942 friendly match away against Slovakia and played 6 games for that team, scoring no goals.
After the war he played for Yugoslavia, collecting another 7 caps and his final international was a September 1947 Balkan Cup match away against Albania.
[1] He later became a manager with Sabadell,[2] Barakaldo CF,[3] UE Sants, Terrassa FC,[4] CE L'Hospitalet.