The 22-year-old winger only joined the Terrors from Rangers last Friday and marked his home debut by giving Jack Ross’s side a priceless lead to defend when they head to the Netherlands next Thursday for the second leg of this Europa Conference League third qualifying round tie.
United, playing their first European match since being thrashed 7-2 on aggregate by Dinamo Moscow in a Europa League qualifier 10 years ago, were backed by a pumped-up home support inside a near-full-house Tannadice crowd of 10,181.
United boss Ross introduced Jamie McGrath – who signed on the eve of the match on loan from Wigan – for his debut in the 59th minute.
It proved an inspired move as the substitute was involved in the hosts taking the lead within two minutes.
Middleton received a pass from Dylan Levitt wide on the right and skipped superbly away from two Alkmaar players before playing a one-two with McGrath and curling home a lovely finish from the edge of the box, sparking delirious scenes inside Tannadice.
Mark Atkinson was at Tannadice and rates the players out of ten ...
1. Mark Birighitti
Australian goalkeeper was a strong presence and made two good stops. Embraced a fan passionately when United opened the scoring. 7 Photo: Rob Casey - SNS Group
2. Liam Smith
Very dependable down the right flank, letting very little get past him. 7 Photo: Ross MacDonald - SNS Group
3. Ryan Edwards
Had a couple of skirmishes with opposition players and picked up a booking, but won most of his duels. 7 Photo: Mark Scates - SNS Group
4. Charlie Mulgrew
Near flawless with his distribution and put in a very assured display at the heart of United's defence. 8 Photo: Ross MacDonald - SNS Group