The Spanish side are our first opponents in Group E, as our European campaign gets under way at 20:00 BST at the Theatre of Dreams.
As United look to emulate our 2016/17 run, which culminated in the Reds lifting the trophy, Ten Hag previewed Thursday's fixture from Carrington.
The boss fielded questions on United's ambitions in the competition, the form of Marcus Rashford, squad rotation, and more.
As the countdown to kick-off continues, read every single word of the Dutchman's briefing below...
Regarding team news, is Anthony Martial still out?
"Yes, he is still out.