Nashville SC defender Walker Zimmerman was the only overage player selected Wednesday for the United States' 25-man training camp roster ahead of its final pre-Olympic friendly, against Japan on June 11 at Kansas City, Kansas.
The U.S. qualified for its first men's Olympic soccer tournament since 2008 and will open against host France on July 24 and play New Zealand three days later, both at Marseille, then finish the first round on July 30 against Guinea at Saint-Étienne.
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Men's Olympic soccer is limited to players under 23, with each team allowed three players over the age limit on its 18-man roster.
Zimmerman, 31, has 42 international appearances and played for the U.S. at the 2022 World Cup.
"We have a big pool of Olympic age group players and then we have three camps so far," coach Marko Mitrovic said in a media availability about the selection of just one overage player. "This is the fourth camp and we want to be sure to evaluate all Olympic age group players and that will affect what overage players will be with us for the Olympic Games.
"We made decision for this camp to have Walker Zimmerman with us and we are very happy. So through these processes, the last seven, eight months, we defined Walker and [center] back as a position of need and with all qualities that Walker has and brings to the table, we are very happy to have him now with us in the camp."
Nineteen of the 25 players picked by coach Marko Mitrovic have appeared for the senior national team, including defender Bryan Reynolds, midfielders Gianluca Busio and Tanner Tessmann, and forwards Paxten Aaronson, Cade Cowell and Kevin Paredes.
Ten players are from Major League Soccer.
Mitrovic's section process is complicated by the U.S. men's national team being involved in the Copa América between June and July and the fact that the Olympics are not part of the FIFA calendar, meaning clubs are not required to release their players.
"There is a possibility for some guys to play both Copa América and Olympic games," Mitrovic said. "We are working on that. Obviously we know that it's not going to be easy to get the players for that and I think this is going to be very case by case, player by player.
"We cannot put them in the same bracket as all the players because it's very, very, very [different]. We know they all play in different parts, different clubs have different approaches and some players had a different load during the season and for some players it would be easier to play both tournaments than others. So that's why I'm saying it's case by case."
Among the omissions were Chicago goalkeeper Chris Brady, Salt Lake midfielder Diego Luna and Dallas winger Bernard Kamungo.
"Diego is one of the players that we are considering," Mitrovic said when asked about the omission of Luna. "He was in consideration for November camp. Unfortunately he was injured in March camp.
"There are some other guys there that we want to evaluate and doors are open for every player. For Diego not being in June camp -- for any other player that is not in June camp -- it doesn't mean that they're not going to be for the Olympic Games."
The roster:
Goalkeepers: Patrick Schulte (Columbus), Gaga Slonina (Chelsea, England).
Defenders: Nathan Harriel (Philadelphia), Jalen Neal (LA Galaxy), Bryan Reynolds (Westerlo, Belgium), John Tolkin (New York Red Bulls), Jonathan Tomkinson (Norwich, England), Caleb Wiley (Atlanta), Walker Zimmerman (Nashville).
Midfielders: Cole Bassett (Colorado), Gianluca Busio (Venezia, Italy), Benjamin Cremaschi (Miami), Jack McGlynn (Philadelphia), Aidan Morris (Columbus), Rokas Pukstas (Hajduk Split, Croatia), Tanner Tessmann (Venezia, Italy).
Forwards: Paxten Aaronson (Eintracht Frankfurt, Germany), Esmir Bajraktarevic (New England), Taylor Booth (Utrecht, Netherlands), Cade Cowell (Guadalajara, Mexico), Damion Downs (Cologne, Germany), Johan Gomez (Eintracht Braunschweig, Germany), Duncan McGuire (Orlando), Kevin Paredes (Wolfsburg, Germany), Griffin Yow (Westerlo, Belgium).
Information from ESPN's Jeff Carlisle contributed to this report.