[USA UNDER-20 MEN] Dillon Serna, who recently signed with the Colorado Rapids as a homegrown player out of the University of Akron, joined the U.S. under-20 national team as the final player on its 20-player squad for the Concacaf U-20 Championship that starts Monday in Puebla, Mexico.

Coach Tab Ramos announced an initial 18-player roster as the team traveled to Toluca, Mexico, to begin training for the tournament. He added German-American Jerome Kiesewetter and Serna to fill out the roster.

Several top U-20 candidates for the backline were unavailable. John Anthony Brooks is starting for German second division leader Hertha Berlin, Birmingham City's Will Packwood is sidelined with a broken leg, and Walker Zimmerman, taken by FC Dallas in the first round of the 2013 MLS SuperDraft, is also injured.

Liverpool added 18-year-old midfielder Marc Pelosi to its Europa League roster, but he won't travel with the Reds for their game on Thursday at Zenit St. Petersburg.

The U-20s open play in the group stage against Haiti Monday and faces Costa Rica four days later at Estadio Olimpico Universitario Lobos BUAP in Puebla, Mexico. They beat Jamaica, 2-1, and tied Jamaica, 1-1 in a pair of warmup games.

U.S. U-20 Roster:
GOALKEEPERS (3): Cody Cropper (Southampton/ENG), Kendall McIntosh (Santa Clara Univ.), Zackary Steffen (FC Delco)
DEFENDERS (5): Eric Miller (Creighton Univ.), Juan Pablo Ocegueda (Guadalajara/MEX), Boyd Okwuonu (Univ. of North Carolina), Shane O’Neill (Colorado Rapids), Javan Torre (UCLA)
MIDFIELDERS (6): Luis Gil (Real Salt Lake), Benji Joya (Santos/MEX), Mikey Lopez (Sporting Kansas City), Dillon Serna (Colorado Rapids), Caleb Stanko (SC Freiburg/GER), Wil Trapp (Columbus Crew)
FORWARDS (6): Brandon Allen (Georgetown Univ.), Daniel Cuevas (Santos/MEX), Daniel Garcia (Univ. of North Carolina), Jerome Kiesewetter (VfB Stuttgart/GER), Mario Rodriguez (Kaiserslautern/GER) Jose Villarreal (LA Galaxy)