Two teenagers have been given the chance to prove they are good enough to replace the retired Mark Delaney in the Wales squad.
Manager John Toshack was hit on Wednesday by confirmation that Delaney had reluctantly decided to give up the battle to recover from three serious knee injuries.
The Aston Villa man was Toshack's most experienced defender, but now he has to quickly find alternatives with the last batch of Euro 2008 qualifiers later this season.
So he has promoted Cardiff's Chris Gunter and Oldham's Neil Eardley from the under-21 squad and added them to the senior party that travels to Bulgaria on Monday for a friendly, due to be played in Bourgas on Wednesday.
From Toshack's point of view, he has to find alternatives to Delaney quickly so there was little point in leaving the two 18 year-olds in the under-21 squad that plays Sweden in Hallmstad on Tuesday.
Toshack has also lost West Ham defender James Collins, who has withdrawn from the senior squad with a groin injury, while Wrexham's Steve Evans is also doubtful.
Gunter, 18, has already won his first cap in last season's friendly draw with New Zealand, a game that saw Eardley on the bench.
But the Oldham youngster has much more first-team experience than his Cardiff rival and is expected to be given the chance to impress against Bulgaria.
Under-21 coach Brian Flynn has now lost a clutch of youngsters from a squad due to fly out from Heathrow on Monday.
Crystal Palace's Rhoys Wiggins has also been forced to withdraw, seemingly with some problems with his recovery from a serious cruciate knee ligament injury that kept him out for a year.
Flynn has added Wrexham's Neil Taylor and Walsall's Mark Bradley to the under-21s. Taylor is the under-19 skipper, and Bradley made his under-21 debut in Northern Ireland last season. Lincoln's Owain Warlow has been called in to replace Wiggins.