The manager spoke to club media at the Benito Villamarin Stadium on Wednesday night, in his usual pre-match Q&A ahead of Thursday's clash with Real Betis.
Ten Hag's men hold a 4-1 lead going into the second leg of our last-16 tie against the La Liga side, following the first-leg triumph at Old Trafford last week.
The likes of Antony, Anthony Martial and Alejandro Garnacho are not in the squad that travelled to Seville, due to injuries or illness, but Erik says that while he is disappointed to lose the trio - as well as other absentees such as Christian Eriksen and Donny van de Beek this season - other Reds now have the opportunity to step up and stake their claim.