MLS deputy commissioner Ivan Gazidis told the Associated Press that Adu's agent Richard Motzkin had confirmed the deal.

The 18-year-old attacking midfielder arrived in the Portuguese capital yesterday to negotiate terms. There were no immediate plans to introduce the player to the media.

"Freddy, when we signed him, was one of most talented young players in the world. I think, today, he still is one of most young talented players in the world," Gazidis said. "What we've struggled with is the expectations, not that we've placed on him, but that the media has placed on him."

MLS and Benfica agreed last week to a $2 million transfer fee for Adu, the U.S. captain at the under-20 World Cup in Canada in July.

Besides the transfer fee, MLS is in position to gain a percentage of any future transfer of Adu from Benfica to another club, Gazidis said.

Adu signed with D.C. United in 2003 at age 14, becoming the youngest player in the league's history. Real Salt Lake acquired Adu from D.C. United last year knowing that when he turned 18 last month he would become eligible under FIFA rules to join a foreign club.

"Freddy's been very devoted to working hard, being a contributor," Gazidis said. "He became a better and more mature player. He's still only 18. When we step outside world of MLS, a good league with veteran players and put him with his peers on a world stage — and peers that are older than him — Freddy clearly has progressed."

Adu missed more than a month of Real Salt Lake's season while he captained the U.S. team to the quarterfinals of the FIFA Under-20 World Cup. Adu had three goals and four assists as the Americans went 3-1-1 in the tournament.

Benfica is one of Europe's storied clubs, having won the European championship in 1961 and '62 while led by the great Eusebio. However, Benfica has faded, winning the Portuguese title only once in the last 13 years. It finished third in the league last season.

The 18-club Portuguese Super Liga is one of Europe's second-tier championships. Only three clubs — Benfica, Sporting Lisbon and FC Porto — make enough money to compete with their continental rivals.