LILLE, France (AP) Belgium knew that replacing two seasoned defenders was never going to be easy in its European Championship quarterfinal against Wales.
However, it turned out to be impossible on Friday.
In a game that highlighted its defensive problems, Belgium lost 3-1, and thus the chance to reach its first semifinal of a major competition since the 1986 World Cup.
Coach Marc Wilmots went into Euro 2016 without injured regulars Vincent Kompany and Nicolas Lombaerts. For the Wales game, he also had to do without Thomas Vermaelen, who was suspended for a second booking.
And as if things couldn't get any worse, Wilmots then had to strike a fourth experienced defender off his list when Jan Vertonghen tore his ligaments in the final training session the day before the game.
Their replacements? Jason Denayer and Jordan Lukaku, both 21, and earning only their eighth and fifth caps, respectively.
''You can't really replace experience. I am in charge of that and we can't blame the young players,'' Wilmots said. ''You need a well-oiled machine to win. We made mistakes we shouldn't have made.''
Belgium certainly made mistakes. After a strong opening 20 minutes and a deserved lead thanks to Radja Nainggolan's 25-meter strike, the midfield started to pull back and the pressure on the young defense became visibly more intense.
Belgium's left wing was especially vulnerable, with Lukaku regularly gesturing and waving his arms, looking unsure as to where to stand or who to mark.
Lukaku tried to play more forward in the second half but failed to make an impact. He was released from his suffering after 75 minutes, replaced by Dries Mertens, as Wilmots sacrificed a defender for a midfielder in Belgium's push for an equalizer.
Wales led 2-1 at the time, with both goals having exposed Belgium's defensive weaknesses.
Wales captain Ashley Williams was hardly hindered by Lukaku when he headed in for the equalizer from a corner taken by Aaron Ramsey.
And in the second half, striker Hal Robson-Kanu picked up a cross by Ramsey from the right wing with his back to the goal, evaded three defenders with a clever move, and beat Belgium keeper Thibaut Courtois with a shot to put Wales ahead.
The gamble on swapping Lukaku for Mertens then backfired, as a large gap opened up on Belgium's left wing. Chris Gunter surged into that space and delivered the cross for Wales' third goal, a header by substitute Sam Vokes. Denayer misjudged the cross while Toby Alderweireld lost the duel in the air with Vokes.
Center back Thomas Meunier acknowledged ''we were just not good enough tonight.''
Apart from the defensive errors, Belgium also paid for a lack of cutting edge up front. Meunier provided a perfect cross early in the second half for Romelu Lukaku, Jordan's older brother, but the striker headed wide - having also squandered a clear chance in the first half.
''We were not efficient enough to kill the game off,'' Meunier said. ''We thought it would be a 50-50 game. There was only one way - win or lose. And we lost.''
Midfielder Axel Witsel said he always knew it would be a tough task to replace Vermaelen and Vertonghen.
''They are two very important players,'' Witsel said. ''We had no other option than to do as well as we can.''
Wilmots said he took full responsibility for fielding young, inexperienced players.
And he brushed aside the consequences the defeat for him personally, highlighting the challenges he faced at the back.
''I take no decisions when the adrenaline is still flowing. At this moment, I don't think about quitting,'' Wilmots said. ''That was the best we had at this moment in time. You can't come up with a new defense in one day.''