Moroni started on the wing in the final Pool C match against Namibia but returns to his usual position in midfield against the Irish.
Juan Martin Hernandez moves back to inside centre to make way for the return of flyhalf Nicolas Sanchez, while Martin Landajo is preferred to Tomas Cubelli at scrumhalf.
"We believe this is our best team to face this match," coach Daniel Hourcade told the Argentine Rugby Union on Friday, adding that Ireland had proved at the World Cup that they are clearly the best team in Europe.
"They have a style similar to the southern hemisphere teams, committing few people in the contact areas and being accustomed to having the ball a lot of the time," Hourcade added.
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"They have great ball winning, a fantastic lineout, they are very patient, play well, don't get desperate."
Argentina have beaten Ireland in two of their three World Cup meetings.
"Those are statistics that have no influence, the players don't have them on their minds," Hourcade said.
"There are other types of statistics that matter, like Ireland having above 60 percent of possession in all their recent matches and 70 in one half against France."
Veteran back-row forward Juan Manuel Leguizamon has not recovered from injury and was left out of the squad for the match at the Millennium Stadium.
"The most important thing is to get control of the game," flanker Juan Martin Fernandez Lobbe said.
"As soon as you can play with confidence you can put doubt in the other team. They can make the wrong decision and that can be the difference."
Team: 1-Marcos Ayerza, 2-Agustin Creevy (captain), 3-Ramiro Herrera, 4-Guido Petti, 5-Tomas Lavanini, 6-Pablo Matera, 7-Juan Martin Fernandez Lobbe, 8-Leonardo Senatore; 9-Martin Landajo, 10-Nicolas Sanchez, 11-Juan Imhoff, 12-Juan Martin Hernandez, 13-Matias Moroni, 14-Santiago Cordero, 15-Joaquin Tuculet
Replacements: 16-Julian Montoya, 17-Lucas Noguera, 18-Juan Pablo Orlandi, 19-Matias Alemanno, 20-Facundo Isa, 21-Tomas Cubelli, 22-Jeronimo De La Fuente, 23-Lucas Gonzalez Amorosino
(Editing by David Goodman)
