At the 2023 WDF World Championship, Duff began his title defence with a 3–1 win over Moreno Blom.[9] In the next round, he went 2–1 down against Martyn Turner but won the match 3–2 to progress to the quarter-finals.[10] Duff's title defence was ended by Chris Landman who defeated Duff 4–3.[11] Despite the exit, Duff was ranked number one in the WDF World Rankings after the tournament after players won PDC Tour Cards at 2024 Q-School, leading to their removal from the WDF rankings.[12]
At the 2024 WDF World Championship, Duff reached the quarter-finals. He went 3–0 down to Jason Brandon but won the next three sets to level the match at 3–3. However, Brandon won the last set to beat Duff 4–3.[13]
Personal life
Duff worked as a joiner before becoming a full-time professional darts player.[2]