Denis Duga

FK Senica

In August 2017, it was announced that Duga would be returning to Slovakia to join First Football League club FK Senica. He was considered the most experienced player in the squad at the age of only 22. He made his debut for Senica in a 1–0 home defeat in the league against FC Nitra. Duga's first contribution came in a 3–1 loss against Spartak Trnava, assisting a goal scored by Jurij Medveděv in the 70th minute. Duga scored his first goal for the club in a 2–2 draw against ŠK Slovan Bratislava, scoring in the 46th minute to make the score 2–1 in favor of the opponents. Four minutes after half time, Oliver Podhorín would score the equalizing goal for Senica.

Zlaté Moravce

In 2018, Duga joined fellow league outfit side FC ViOn Zlaté Moravce. He made his first division debut for ViOn in a 1–0 away victory against his former club, FK Senica. Duga scored his first goal for the club 2 seasons after his debut, scoring in the 21st minute of the game in a 2–1 loss against FC DAC 1904 Dunajská Streda. He experienced relegation with the club in the 2023–24 season. He signed an extension to his contract with ViOn in 2024 alongside several other players.

Duga once played for the Slovakia national under-21 football team under coach Pavel Hapal while playing for Slavia Prague in the youth category.