London - Defenders Ben Davies and James Collins were absent from the Wales squad announced by manager Chris Coleman on Tuesday for next month's 2016 European Championship qualifying showdown with Belgium.
Tottenham Hotspur left-back Davies dislocated his shoulder during his side's 2-2 Premier League draw at Southampton a month ago, while experienced West Ham United centre-back Collins has sustained a calf strain.
It leaves Coleman missing two important members of his back four ahead of the June 12 encounter with Belgium at the Cardiff City Stadium.
Belgium currently lead Wales on goal difference in qualifying Group B, with Israel two points back in third place.
The top two teams will qualify for next year's tournament in France, with the third-place side either qualifying directly -- if they are the best third-place team in the nine groups -- or going into the play-offs.
Real Madrid forward Gareth Bale and Arsenal midfielder Aaron Ramsey are the stand-out names in Coleman's 23-man squad.
Leicester City midfielder Andy King returns after a two-match ban, while defenders James Chester, Paul Dummett and Adam Matthews are recalled after missing the 3-0 away win over Israel in March through injury.
Wales, who drew 0-0 away to Belgium in November, are bidding to reach their first major tournament since the 1958 World Cup.
Wayne Hennessey (Crystal Palace/ENG), Owain Fon Williams (Tranmere Rovers/ENG), Daniel Ward (Liverpool/ENG)
Ashley Williams (Swansea City, capt), James Chester (Hull City/ENG), Chris Gunter (Reading/ENG), Neil Taylor (Swansea City), Paul Dummett (Newcastle United/ENG), Adam Matthews (Celtic/SCO), Jazz Richards (Swansea City), Adam Henley (Blackburn Rovers/ENG)
Joe Allen (Liverpool/ENG), Joe Ledley (Crystal Palace/ENG), Aaron Ramsey (Arsenal/ENG), Andy King (Leicester City/ENG), David Vaughan (Nottingham Forest/ENG), Shaun MacDonald (Bournemouth/ENG)
David Cotterill (Birmingham City/ENG), Hal Robson-Kanu (Reading/ENG), Tom Lawrence (Leicester City/ENG), Gareth Bale (Real Madrid/ESP), Simon Church (Charlton Athletic/ENG), Sam Vokes (Burnley/ENG)