In 2016, Ducas debuted for the Geraldton Buccaneers in the State Basketball League (SBL), averaging 2.27 points in 22 games.[4] In 2017, he played 13 games for the Buccaneers, averaging 5.67 points and 1.47 rebounds per game.[5] He also played five games for the BA Centre of Excellence in the South East Australian Basketball League (SEABL), averaging 2.4 points and 1.2 rebounds per game.[6] In 2018, he averaged nine points in three SBL games for the Buccaneers[7] before returning to the Centre of Excellence and averaging 12.2 points, 2.1 rebounds and 1.5 assists in 14 SEABL games.[8]
In 2019, Ducas played nine games for the Centre of Excellence in the NBL1, averaging 21.8 points, 3.6 rebounds, 1.4 assists and 1.0 steals per game.[9] He finished the year with the Buccaneers and helped them win the SBL championship.[10] In 13 games, he averaged 15.54 points, 3.92 rebounds and 3.08 assists per game.[11]
On 5 November 2019, Ducas made his debut for Saint Mary's, recording 3 points and 2 rebounds against Wisconsin.[14] As a freshman, Ducas appeared in 33 games, starting in 11 games – which was more games as a true freshman than any Gael since Matthew Dellavedova.[15] In his sophomore season, Ducas suffered an ankle injury, causing him to appear in only 14 games. Prior to his injury, Ducas averaged 11.3 points on 35.7% from three.[15] He posted 10.3 points per game as a junior.[16] As a senior, Ducas averaged 12.5 points per game shooting 41.4% from beyond the arc.[17]
In his final season with Saint Mary's, Ducas started every single game for the third consecutive season, shooting a career-best 43.8% from three, making 81 – which was the ninth most in team history and second most in the WCC.[15] Against Davidson, Ducas registered a season-high 23 points on 7 made threes.[18] With Saint Mary's, Ducas won the 2024 WCC tournament and was named a second team All-WCC honoree for the second time.[19] Ducas averaged 9.9 points, 5.6 rebounds and 1.9 assists per game.[17]
As a fifth year guard, Ducas finished his collegiate career playing in a program-record 150 games and finished second all-time in program history with 278 threes.[20]
