Duk was hired as the first head coach of the Borregos Salvajes CEM for their debut season in ONEFA in 1994, where they began in the second-tier National Conference.[3] He led the team to its historic first win in their opening game, beating the Toros Salvajes Chapingo [es] 39–27.[3] Duk guided the team to a 6–1 record and an appearance in the National Conference championship game, where they lost 13–0 to the Panteras Negras UAM.[3] After losing in the championship game again the following year, the team was successful in its third attempt, defeating the Lobos UAdeC [es] 28–6 in the 1996 National Conference championship game after an undefeated season and earning promotion to the 10 Grandes Conference – the highest ONEFA tier.[3][4]
In 2000, Duk led the Borregos Salvajes CEM to another undefeated season and its first-ever ONEFA national championship, defeating the Borregos Salvajes Monterrey 38–28 in the 10 Grandes Conference final.[4][5] He earned five consecutive ONEFA Coach of the Year awards from 1996 to 2000.[4] Duk quit following the 2001 season, in which his team was eliminated in the semifinals by the Auténticos Tigres UANL.[6][7]
Duk won a Liga OMFA Pro [es] championship in 2002 as head coach of the semi-pro Pieles Rojas A.C.[4] In 2003, he coached the Lobos UAdeC of the Autonomous University of Coahuila, though the team finished the season with a losing record.[8] He returned to the semi-pro ranks after that, coaching the Petroleros de Pemex in 2004 and the Pieles Rojas A.C. in 2005.[4]
Duk took the reins of the Linces UVM of the Universidad del Valle de México in 2005 as the new team's first-ever head coach.[9][10] In his first season, he led the team to a promotion to the top-tier 12 Grandes Conference after winning the second-tier National Conference title.[10][11] Duk earned his sixth ONEFA Coach of the Year award and became the first head coach to achieve promotion to the top tier with two different teams.[4] He was replaced by Roberto Cervantes, his defensive coordinator, following the 2012 season.[12]
Duk was subsequently offered the head coaching job of the Toros Salvajes Chapingo, but was unable to accept for personal reasons.[2]
In November 2015, Duk was announced as the first head coach of the Raptors de Naucalpan, members of a new professional spring league called the Liga de Fútbol Americano Profesional (LFA).[13] In the league's inaugural season in 2016, the team finished the season with a 4–2 record and reached Tazón México I, the first edition of the LFA championship game, where they lost 29–13 to the Mayas CDMX.[14][15]
In 2017, Duk led the Raptors to a 5–2 record and a first-place finish in the North Division, with league MVP Bruno Márquez at quarterback. However, they were eliminated in the first round of the playoffs after suffering a 13–10 defeat to the Dinos de Saltillo.[16]
In October 2017, Duk joined another LFA team, the Mexicas CDMX, as their new head coach.[17] In his only season with the team, he led the Mexicas to its first league championship with a 17–0 victory over the Raptors de Naucalpan in Tazón México III after finishing the regular season with a 4–3 record.[18][19]
In September 2018, Duk was announced as the head coach of the Bulldogs de Naucalpan of the Liga de Football Pro (later Fútbol Americano de México), a new football league that began its inaugural season that February to compete with the LFA.[20]
In 2019, Duk was named the sixth head coach in the history of the Búhos IPN program, which was returning to Mexican football for the first time since 1985.[21][22] In his first year at the helm, he led the team to an undefeated season capped off by a 41–15 victory over the Lobos Plateados IPN to win the FADEMAC league title.[22][23] The 2020 season was cancelled due to the COVID-19 pandemic. In 2021, the Búhos returned to ONEFA, after a 36-year absence, as a member of its Center-South Conference.[21][22] Duk led the team to a 3–1 record, sitting atop of the Group A standings when the rest of the season was also cancelled.[22][24] The Búhos subsequently won the third-tier National Central Conference title in 2022, defeating the Frailes del Tepeyac [es] 20–17 in the final.[25][26]
Duk was named the head coach of the Burros Blancos IPN [es] ahead of the 2023 season.[27][28]
Duk served as the offensive coordinator for the Mexico national team at the 1999 IFAF World Championship held in Italy, helping the team win a silver medal.[4] He won another silver medal at the 2003 edition held in Germany, this time as an assistant head coach.[4]
As a head coach, Duk led Team Mexico to bronze medals at the 2003 and 2007 NFL Global Junior Championships held in San Diego and Miami, respectively.[1] He also commandeered the Mexico under-19 national team to consecutive bronze medals at the 2014 and 2016 editions of the IFAF U-19 World Championship held in Kuwait and China, respectively.[1]
Mexico
