Duffy played for Dundalk in nine Europa League games this season, including both against Arsenal in the group stage. He had a two-year spell at Celtic without breaking into the first team.
FIFA has also processed the Canadian association’s request to select former Portugal defender Ricardo Ferreira.
The Canada-born former AC Milan player was able to switch because his one selection by Portugal was not in a competitive game. Ferreira played in a 2017 friendly against the United States, which gave teenagers Weston McKennie and Tyler Adams debuts that day.
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