Centre-back De Ligt has been a growing influence on Amorim's side over recent months and was one of our March Player of the Month nominees, before missing Sunday's Manchester derby with an injury picked up in the previous game, away to Nottingham Forest.
Collyer, meanwhile, was an unused sub at Forest but also absent for the derby. The midfielder recently suffered a knock and, like De Ligt, will not play in Thursday's tie at the Groupama Stadium, from where Ruben Amorim spoke about both players in his pre-match press conference.
"Matta has a problem in his foot, we are trying to assess.