FC Dallas forward Jesus Ferreira, Philadelphia Union midfielder Brenden Aaronson and Colorado Rapids left back Sam Vines, along with LA Galaxy academy product Ulysses Llanez, are the four debutants in the youngest XI the US has ever fielded during a January camp. FCD right back Reggie Cannon is the additional Homegrown in the lineup.
Ferreira makes his debut after being granted a waiver to represent the US by FIFA on Friday.
Six players in head coach Gregg Berhalter's starting XI are age-eligible for the 2020 Olympic qualifiers in March: Aaronson, Cannon, Ferreira, Llanez, Vines and San Jose Earthquakes midfielder Jackson Yueill.
Three current MLS players were named in an experienced Costa Rica lineup: D.C. United's Ulises Segura, NYCFC's Ronald Matarrita and the Galaxy's Giancarlo Gonzalez. There are also four former MLSers in the starting lineup, with four more current players on the bench.