Aaron Ramsey and David Brooks are among four Wales players to withdraw from the squad for their upcoming Nations League double-header.
Juventus midfielder Ramsey and Bournemouth winger Brooks, who missed the majority of last season with an ankle injury, are joined by Bristol City defender Ashley Williams and Leeds forward Tyler Roberts on a list of absentees announced by the Football Association of Wales on Sunday night.
Brooks has pulled out due to further ankle trouble, which ruled him out of Bournemouth's 2-1 pre-season friendly defeat to Benfica in Portugal on Sunday night.
Liverpool forward Ben Woodburn and Nottingham Forest's teenage midfielder Brennan Johnson have been added to the squad to cover the absences.
Wales confirmed the withdrawals in a brief statement on Twitter, which read: "Aaron Ramsey, David Brooks, Tyler Roberts and Ashley Williams all withdraw from the senior squad.
"Ben Woodburn and Brennan Johnson are called up from the U21s as replacements."
The original squad announced on Tuesday featured first senior call-ups for Liverpool teenager Neco Williams and fellow defender Ben Cabango of Swansea.
Ryan Giggs also included Hal Robson-Kanu, who is back in the fold after making himself available again following his decision to retire from international football in 2018.
Giggs' side face Finland away on September 3 and host Bulgaria three days later.