Tottenham defender Ben Davies will miss Wales' two Euro 2020 qualifiers in June because of a hernia operation.
The 26-year-old, who is in Madrid preparing for the Champions League final, has had pain all season and needs surgery to make a full recovery.
Wales will also be without injured Aaron Ramsey, but Ethan Ampadu is over a back injury, while boss Ryan Giggs includes four uncapped players.
They face Croatia in Osijek on 8 June and Hungary in Budapest on 11 June.
Giggs included seven uncapped players in a squad that trained last week in Portugal.
The ones to remain involved are Manchester United teenager Dylan Levitt, Swansea City's Joe Rodon, Kieffer Moore and his Barnsley team-mate Ben Williams.
Swansea winger Daniel James is included, having missed the training camp following the death of his father.
Davies is getting ready for Tottenham's Champions League final against Liverpool on Saturday (20:00 BST).
He hopes to be involved in that showpiece, but the hernia procedure's six-week rehabilitation period means he needs to have the operation next week, ruling him out of the games against Croatia and Hungary.
The former Swansea left-back is disappointed to miss the two games but feels he must make this sacrifice in order to recover and have a full pre-season programme before the next campaign.
It could be a busy season for Davies, who will hope it lasts until next summer with Wales qualifying for Euro 2020.
Continuing to play with his long-standing hernia problem could have hampered his chances of potentially playing at that tournament, so Davies was advised to have surgery as soon as possible.
In his absence, Davies hopes Wales can build on their opening qualifying win over Slovakia when they travel to Croatia and Hungary.
"These are massive games," Davies told BBC Sport Wales.
"That first win was huge and the way the group's gone so far, if we can pick up one win, we're putting ourselves in a great position.
"Two tough games away - three or four points will stand us in good stead to kick on for the last few."
Newcastle's Paul Dummett and Leeds forward Tyler Roberts are not included in the squad because of injury.
Wales squad: Hennessey (Crystal Palace), Ward (Leicester City), A Davies (Barnsley), A Williams (Everton, on loan at Stoke), Taylor (Aston Villa), Mepham (Bournemouth), Gunter (Reading), Roberts (Swansea City), B Williams (Barnsley), Ampadu (Chelsea), Rodon (Swansea City), Lockyer (Bristol Rovers), J Lawrence (Anderlecht), Allen (Stoke City), J Williams (Charlton Athletic), Vaulks (Rotherham United), Brooks (Bournemouth), Smith (Manchester City), Levitt (Manchester United), James (Swansea City), Bale (Real Madrid), Woodburn (Liverpool), Wilson (Liverpool, on loan at Derby County), T Lawrence (Derby County), Matondo (Schalke 04), Thomas (Leicester City, on loan at Scunthorpe United), Vokes (Stoke City), Moore (Barnsley).