The 20-year-old American forward joined Greek club Aris on Jan. 6 in an 18-month loan from Benfica, where he had struggled. He had previously been loaned to smaller Portuguese club Belenenses.
"Football in Europe is No. 1 and where it's at its best. This is why I decided to come to Europe," he said Thursday in his first official appearance with the team.
Adu will play left midfield for Aris and join U.S. striker Eddie Johnson, who is on loan from Fulham.
Adu said he was grateful for being sought by Aris coach Hector Raul Cuper, an Argentine who has previously managed Inter Milan and other Spanish and Italian clubs.
"I finally have a great chance to play for one of the top-class coaches in the world," Adu said. "I've only been here for two weeks and I can't believe how much I've learned."
Aris hosts league leader Panathinaikos on Sunday, when Adu hopes to make his debut.
"What a great way to play your first game, against the No. 1 team in the league. I can't wait to go on Sunday," he said. "I would really, really love to be a part of that game."
Adu is vying for a spot on the U.S. national team, which will head to its sixth straight World Cup appearance in June in South Africa.