The 16 year old Galway light welter, the youngest member of the Irish team, won his opening bout at the World Youth Championships in St Petersburg following a brilliant performance.
The Olympic BC fighter took on American Fredius Rojas Jr in the Round of 32 and emerged a split decision victor following an hellacious scrap.
A cagey battle of the jabs in the first, gave way to a more toe-to-toe affair in the second. This continued into the third where Dossen wobbled his Las Vegas opponent with a huge shot and saw out the win.
It was the first time that former Irish High Performance Unit coach Billy Walsh cornered an American fighter against his homeland, and the tenacious Dossen ensured that it would be a losing return for Walsh.
Dossen will now fight Hugo Micallef of Monaco tomorrow morning in the Last 16.
Earlier on this morning, Dublin light flyweight Jordan Moore bowed out, following a close split-decision loss in his Last 16 bout with Filipino Carlo Paalan.