Union defenders Mark McKenzie and Matt Real returned to Philadelphia on Sunday from the under-20 World Cup after the United States lost in the quarterfinals to Ecuador on Saturday.

Just as they were flying home from Poland, defender Auston Trusty and midfielder Brenden Aaronson left for a U.S. under-23 team training camp in suburban Salt Lake City that will evaluate prospects for the 2020 Olympic team. The camp runs through June 16.

Trusty, Aaronson and 13 other MLS-based players among the 21 total called in will thus miss this week’s round of U.S. Open Cup games, in which all 21 American MLS teams enter the tournament.

There is an understandable desire to boost the Olympic team’s importance, as the U.S. men failed to qualify for the 2012 and 2016 tournaments. But why this camp has to overlap with the Open Cup instead of running between the two rounds in June - this week’s winners play again in the middle of next week - is unclear.

The Open Cup, which U.S. Soccer runs, has long been a breeding ground for young American players because teams are limited to five foreigners in the game-day squad of 18. This camp thus hamstrings teams for which young Americans matter.

Here’s the full U.S. roster:

Goalkeepers (3): JT Marcinkowski (San Jose Earthquakes), Andrew Thomas (Stanford University), Justin Vom Steeg (Los Angeles Galaxy)

Defenders (6): Marco Farfan (Portland Timbers), Justen Glad (Real Salt Lake), Aaron Herrera (Real Salt Lake), Jack Maher (Indiana University), Sam Rogers (Seattle Sounders), Auston Trusty (Philadelphia Union)

Midfielders (8): Brenden Aaronson (Philadelphia Union), George Acosta (unattached), Mukwelle Akale (Villarreal CF B, Spain), Cameron Lindley (Memphis 901 FC) Sebastian Saucedo (Real Salt Lake), Eryk Williamson (Portland Timbers), Jackson Yueill (San Jose Earthquakes), Gedion Zelalem (Sporting Kansas City)

Forwards (4): Brooks Lennon (Real Salt Lake), Benji Michel (Orlando City), Alfonso Ocampo Chavez (Seattle Sounders), Giovanni Reyna (unattached)