22-year-old midfielder Freddy Adu will train with La Liga side Rayo Vallecano for two weeks ahead of the 2012 Major League Soccer season.
Adu will become the fourth member of the Union to train abroad this offseason. Zac MacMath trained alongside Tim Howard at Everton, Amobi Okugo trained with Bundesliga side SC Freiburgand, and 16-year-old Zach Pfeffer trained with Bundesliga side Hoffenheim.
Okugo, Danny Mwanga, Jack McInerney and MacMath also spent 10 days in Amsterdam training and playing exhibition matches with Generation adidas.
Additionally, Adu, Okugo, McInerney, Williams and MacMath recently finished a nine-day U-23 U.S. National Team training camp in Lakewood Ranch, Fla. in preparation for the 2012 CONCACAF Olympic Qualifying Tournament, which begins March 22 with a match against Cuba. It was the second U-23 call-up of the offseason for McInerney, Okugo and Williams, who participated in head coach Caleb Porter's training camp held from November 7-16 at the Sportschule Wedau in Germany.
Adu signed with the Union on August 12, 2011 on a transfer from Benfica of the Portuguese First Division. In 11 appearances and six starts with Philadelphia, Adu registered two goals and an assist in 609 minutes.
The Union will begin the 2012 regular season March 12 at Portland before returning home for a March 18 home opener against a TBD opponent.