De Gea has been replaced by Dean Henderson as United's No.1 and is set to be sold in the summer.
But Solskjaer will not allow sentiment to cloud his judgement as he looks to land his first trophy as United boss.
Asked whether De Gea will play against Villarreal, he said: “I've got to make difficult decisions before the final – but I feel I've got to make very difficult decisions every time I pick a team.
“We're Man United and we should have competition for every single spot in the team.
“I've always got top quality players on the bench, whether it is centre-forward, right-wing, right-back, centre-midfield or keeper.
“I've said it so many times that I'm the luckiest manager in the world with the two keepers I've got."