“You can always get away with playing young forwards but playing young central defenders away from home, in a game of that magnitude, is going to make for a difficult night. That's how it proved.
“They'll learn from the experience but nonetheless it was a hard night for them.
“From a spectator's point of view it was a terrific game of football. You're getting your money's worth with nine goals, there's no doubt about that!”
Sir Alex was speaking to Sky Sports News and MUTV.
More: Gallery - Cup thriller at the Bridge | Reds' games moved for TV