Players can be called on by their nations between 20 May and 30 June. Eintracht forward Luka Jović in particular will have a busy summer, first with the senior Serbia team before joining up with the U21s at this year's European Championship.
Matches at a glance:
Tuesday 28 May
Panama U20 - France U20 / Evan Ndicka (18:00)
Friday 31 May
Mali U20 - France U20 / Evan Ndicka (18:00)
Friday 7 June:
Denmark - Ireland / Frederik Rönnow (20:45)
Latvia - Israel / Taleb Tawatha (20:45)
Austria - Slovenia / Martin Hinteregger (20:45)
Ukraine - Serbia / Filip Kostic, Mijat Gacinovic, Luka Jovic (20:45)
Gambia - Guinea / Simon Falette (TBA)
Saturday 8 June:
Belarus - Germany / Kevin Trapp (20:45)
Croatia - Wales / Ante Rebic (15:00)
Monday 10 June:
Denmark - Georgia / Frederic Rönnow(20:45)
Poland - Israel / Taleb Tawatha (20:45)
North Macedonia - Austria / Martin Hinteregger (20:45)
Serbia - Lithuania / Filip Kostic, Mijat Gacinovic, Luka Jovic (20:45)
Tuesday 11 June:
Germany - Estonia / Kevin Trapp (20:45)
Croatia - Tunisia / Ante Rebic (20:45)
Benin - Guinea / Simon Falette (TBA)
Sunday 16 June:
Egypt - Guinea / Simon Falette (TBA)
Monday 17 June:
Serbia U21 - Austria U21 / Luka Jovic (18:30)
Thursday 20 June:
Germany U21 - Serbia U21 / Luka Jovic (21:00)
Saturday 22 June:
Guinea - Madagascar / Simon Falette (22:00)
Sunday 23 June:
Denmark U21 - Serbia U21 / Luka Jovic (21:00)
Wednesday 26 June:
Nigeria - Guinea / Simon Falette (16:30)
Sunday 30 June:
Burundi - Guinea / Simon Falette (18:00)
