But in-form ace Antonio Valencia hurt himself setting up the
second goal for Javier Hernandez.
Boss Alex Ferguson said: "He has a hamstring injury,
unfortunately — it'll be four weeks out. It is a bad blow for
us."
United take a two-goal cushion back to Old Trafford for
Thursday's second leg in the last 32.
But they needed an excellent second-half display to see off Ajax
after strikes from Young and Hernandez.
Fergie admitted the first 45 minutes were below standard.
He said: "The result was better than the performance.
"The first half was disappointing.
"It was difficult to get the rhythm and speed to the game.
"We didn't reach any great heights. We improved in the second
half, made some good opportunities and deserved to win.
"It's a good result. You can't complain too much when you win
2-0 away from home.
"Winning is always a good habit. We're in a good spell now.
We're not taking anything for granted at Old Trafford."
Ajax coach Frank de Boer admitted: "There's a difference in
class between the two clubs.
"I don't think we're going to win 3-0 over there!"
