Hopefully, there's something symbolic about the substitution itself. Adnan Januzaj was introduced to Old Trafford against Crystal Palace at the expense of Ashley Young, and the contrast between the two wingers could not have been more stark.
Where Young predictably clunked inside at every opportunity, Januzaj darted this way and that with genuine unpredictability. Where Young plodded, Januzaj attacked with real pace. Where Young pumped in hopeful balls, Januzaj lashed in crosses into dangerous areas towards dangerous men. Where Young went for the easy option, Januzaj produced something special.
This was quite a prodigious performance, but the highlights (and that there are so many packed into just half an hour ought to speak volumes):
0:14: His excellent understanding with Patrice Evra (who ought to be mentioned as having an exceptional start to the season)
1:18: An excellent first touch, followed by a smart turn and a clever ball to find Antonio Valencia. What other play do we have capable of pulling this off? Even Shinji Kagawa seems a stretch based on his performances for the club so far.
2:41: The combination of two-footedness, pace, dribbling, and creativity makes him a highly unpredictable prospect when running down the wing - the defender cannot guess what he's going to do, and showing him onto any foot or into any position would not negate the danger. The finish was disappointing, but if he can add that to his game, then the completeness of his attacking game will make positions like this pretty much undefendable.
2:57: A superb run and pass, making the right decision at exactly the right time and executing it perfectly.
3:09: His utter determination to get on the ball and make things happen. We have far too little of this in our team now: for a long, long time we've looked like we want to win games while standing still, not offering enough movement and forcing the issue. This, while we may worry about his positional discipline, shows the total opposite of that. It would be interesting to see him in a midfield three if he is capable of such dynamism.