Manchester United boss Sir Alex Ferguson owned up to the selection blunder that nearly cost his side their place in the Europa League at Old Trafford.
Jones: We're bitterly disappointed
Already two goals up against Ajax and with a testing Premier League trip to Norwich looming on Sunday, Ferguson opted to select a youthful defence in which Chris Smalling was the oldest component at 22.
The move nearly backfired spectacularly for, despite taking an early lead through Javier Hernandez, United conceded twice and by the end were one goal away from going out.
"I have to accept responsibility," Ferguson said. "Playing so many young players in the back four was a big ask.
"I thought with a 2-0 lead it was a great opportunity to give Chris Smalling and Phil Jones a game because they have been out for such a long time.
"They have great potential but the lack of experience in terms of tying up the game created a problem for us. For a European night it was too much of a risk. We survived it with a bit of luck but we didn't play well in the second half and it was a nervy night."
United only held on thanks to a superb David De Gea save from Siem de Jong at a time when Ajax were dominating. It was yet another example of the young Spain star's superb reflexes, which have got his side out of trouble on more than one occasion this season.
"De Gea made a tremendous save," said Ferguson. "You think about the size of our team and they got two headers from corner kicks, which you don't expect."
On the plus side, Jones, Smalling and Tom Cleverley - all watched by Stuart Pearce who has named the trio in his England squad to face Netherlands at Wembley next week - gained valuable match practice after significant layoffs which should help United over the coming weeks.
However, Ferguson knows his side will have to improve significantly if they are to overcome Primera Divison outfit Athletic Bilbao in the last 16. "The experienced players will play in that one," he said.
Ferguson also confirmed Wayne Rooney remains a doubt for Sunday's trip to Carrow Road as he struggles to shake off a throat infection. Rooney's presence was missed at Old Trafford with Ajax coach Frank de Boer admitting his side had blown a glorious opportunity.
"I had a feeling there was more to gain," De Boer said. "There was a possibility for us to get a very good result. Even at 3-0 [on aggregate] I thought if we did what we were capable of, we could threaten them.
"I was very angry at half-time and whilst we did better in the second half, we could have caused them much more damage. Of course, Manchester United have the possibility to win it now. There are some good teams in it but they are one of the favourites."