US national team coach Jurgen Klinsmann will evaluate European-based players with an eye to the upcoming World Cup in Wednesday's friendly against Ukraine in Cyprus.
Political upheaval and protests in Ukraine forced the match to be moved to Cyprus, where the Americans will travel after two days of preparation in Frankfurt to face a team that missed out on the World Cup after losing a play-off to France.
In all, 21 Europe-based US players will be called into camp to be joined by Toronto midfielder Michael Bradley, Seattle striker Clint Dempsey and Club Tijuana defender Edgar Castillo.
"This game is a huge opportunity, mainly for our European-based players, to prove to us that they are eager and hungry to jump on the train to the World Cup," Klinsmann said.
"With this game being the only chance for these players before our World Cup preparation camp begins, it's even more important they have a good showing."
The US team will have 18-year-old Bayern Munich dual-citizen forward Julian Green in camp, but he is not yet eligible to play in a match.
"Julian is an exceptional talent," Klinsmann said. "As we have our eyes on the World Cup, we also have our eyes on developing the next generation of players and Julian is a very important part of that."
Klinsmann, a former star international and World Cup coach for Germany, is counting heavily upon Sunderland striker Jozy Altidore, Everton goalkeeper Tim Howard and Besiktas midfielder Jermaine Jones as well as Bradley and Dempsey.
"These five players build our spine," Klinsmann said. "Our team is defined in its spine."
For some players, it will be a defining moment.
Defender Oguchi Onyewu has his first chance with the US squad since helping a Gold Cup title run last July while Bolton defender Tim Ream gets his first call since last August.
Reading midfielder Danny Williams last played for the Americans in a World Cup qualifying loss at Honduras almost 13 months ago but has netted two goals for Reading and started the past 15 matches.
And Will Packwood, a 20-year-old defender at Birmingham City, could earn his first cap.
"It's great to call in players like Oguchi Onyewu, Will Packwood, Tim Ream, who is playing consistently well at Bolton, Danny Williams, who has now kind of made his way through at Reading and playing week-in week-out, and Juan Agudelo, who is now in Holland," Klinsmann said.
Goalkeepers: Cody Cropper (Southampton/ENG), Brad Guzan (Aston Villa/ENG), Tim Howard (Everton/ENG)
Defenders: John Brooks (Hertha Berlin/GER), Geoff Cameron (Stoke City/ENG), Edgar Castillo (Club Tijuana/MEX), Alfredo Morales (Ingolstadt/GER), Oguchi Onyewu (Sheffield Wednesday/ENG), Will Packwood (Birmingham City/ENG), Tim Ream (Bolton Wanderers/ENG)
Midfielders: Alejandro Bedoya (Nantes/FRA), Michael Bradley (Toronto/CAN), Mix Diskerud (Rosenborg/NOR), Fabian Johnson (Hoffenheim/GER), Jermaine Jones (Besiktas/TUR), Sacha Kljestan (Anderlecht/BEL), Brek Shea (Barnsley/ENG), Danny Williams (Reading/ENG)
Forwards: Juan Agudelo (Utrecht/NED), Jozy Altidore (Sunderland/ENG), Terrence Boyd (Rapid Vienna/AUT), Clint Dempsey (Seattle Sounders), Julian Green (Bayern Munich/GER), Aron Johannsson (AZ Alkmaar/NED)