Career
He is a cultured left back. He made his career debut with Hougang United Football Club on 2 February 2010 under the tutelage of then-Cheetahs coach Aide Iskandar before moving over to Woodlands Wellington Football Club in the middle of the 2011 South-League season. He played his first game for the Rams on 2 July 2011.
Duncan is known for being a set-piece specialist and he is a regular corner taker for corners on the right side of the pitch due to his ability to provide in-swinging crosses with his left foot.
During a mid-season report on the 2012 South-League season done in June, Entertainment and Sports Programming Network named Duncan as Woodlands" mid-term player of the season for his consistent performances on the field, a testament to his ability and dependability. On 23 November 2012, it was announced by Woodlands Wellington that he would not be retained for the 2013 season.
On 4 January 2013, it was confirmed that Duncan would be moving to Geylang International during a press conference by the Eagles.