Four Union players will join their national teams during the FIFA window that start next week, meaning they’ll miss the club’s March 23 home game against the Columbus Crew.

Goalkeeper Andre Blake and striker Cory Burke are heading to Jamaica for a March 23 Concacaf Nations League qualfying game at El Salvador and a March 26 friendly at Costa Rica. If the Reggae Boyz beat El Salvador, they’ll qualify for next summer’s Gold Cup and could qualify for the top tier of games in the 2019-20 Nations League cycle.

Midfielder Warren Creavalle will be with Guyana’s national team for a March 23 Nations League qualifier at home against Belize. Guyana can qualify for the Gold Cup with a win, and would likely secure a place in the second tier of 2019-20 Nations League games.

(The qualification process is explained in reasonably plain English on Concacaf’s website.)

Lastly, defender Matt Real is on the U.S. under-20 men’s team roster for a training camp in Spain with friendlies against France on March 22 and Japan on March 25. The camp is the last big get-together for players aiming to impress coach Tab Ramos before the World Cup in May and June.

Fortunately for Real, he doesn’t have to do much impressing. He was a stalwart of the team that won Concacaf’s qualifying tournament last autumn, and is a near-lock to go to the World Cup.

Also on the roster is Philadelphia-born goalkeeper C.J. dos Santos, who plays for the youth team of Portuguese power Benfica.

Union centerback Mark McKenzie was not called up to the under-20s because of his recent concussion from which he has only just recovered. A source said McKenzie’s absence has no bearing on whether he will go to the World Cup. That question remains unsettled as of now.

All four players will leave the Union after this Sunday’s game at Atlanta United (7:15 p.m., PHL17).

Columbus will be missing some of its top players as well. Striker Gyasi Zardes, midfielder Will Trapp and Coatesville-born goalkeeper Zack Steffen will be with the senior U.S. team for friendlies against Ecuador on March 21 and Chile on March 26. Waylon Francis (Costa Rica), Justin Meram (Iraq) and Aboubacar Keita (U.S. U-20s) will also be gone.

The Union-Crew game is one of five MLS games during the FIFA window. MLS has cut down on games in FIFA windows in recent years, but it’s still necessary at times due to teams’ congested schedules.

U.S. under-20 team roster

Goalkeepers (2): C.J. Dos Santos (Benfica, Portugal), Trey Muse (Seattle Sounders)

Defenders (6): Sergino Dest (Ajax, Netherlands), Chris Gloster (Hannover 96, Germany), Aboubacar Keita (Columbus Crew), Jaylin Lindsey (Sporting Kansas City), Matthew Real (Philadelphia Union), Chris Richards (Bayern Munich, Germany)

Midfielders (6): Frankie Amaya (FC Cincinnati), Christian Cappis (Hobro, Denmark), Andrew Carleton (Atlanta United), Chris Durkin (D.C. United), Alex Mendez (Freiburg, Germany), Juan Pablo Torres (New York City FC)

Forwards (6): Ayo Akinola (Toronto FC), Jonathan Amon (Nordsjaelland, Denmark), Konrad de la Fuente (Barcelona, Spain), Ulysses Llanez (Unattached), Justin Rennicks (New England Revolution), Sebastian Soto (Hannover 96, Germany)