- Manchester United reach Europa League last 16 despite second leg defeat
- Ajax win 2-1 at Old Trafford but lose 3-2 on aggregate
- Valencia go through with 1-0 win over Stoke and 2-0 on aggregate
- Atletico Madrid join strong Spanish contingent in last 16
United led 2-0 from the first leg in Amsterdam last week and looked set to cruise through when Javier Hernandez put them ahead with a well-taken early goal.
But Ajax leveled the match later in the first half through a low shot from Aras Ozbiliz and when Toby Alderweireld headed them with four minutes to go United were rocking.
Alex Ferguson's men had thrown away leads during their failure to qualify from the group stages of the Champions League and this was another reminder.
But they were able to play out time to lose 2-1 on the night but go through 3-2 on aggregate and will face Athletic Bilboa in the next round.
Ferguson admitted his youthful selection had nearly cost them their passage through.
"I must say, I've got to accept I'm responsible for picking the team and tonight I picked too many young players in the back four positions -- that was a big problem in terms of experience. It was a big risk I took," he told Channel Five.
"We only had one shot in the second half. I thought we were very poor in the second half," he added.
Bilboa's Spanish counterparts Valencia, like City and United among the favorites to lift the Europa League title, also went through with a 1-0 home win over Stoke City.
They led the English Premier League side 1-0 from the first leg and scored the only goal of the return in the Mestalla through Jonas after 24 minutes.
On a good night for La Liga sides, Atletico Madrid also qualified for the last 16 as they beat Lazio 1-0 at home to go through 4-1 on aggregate against the Italians.