The 25-year-old limped off in the 35th minute after he appeared to injure himself in the build-up to Brentford’s second goal.
According to Manchester Evening News journalist Tyrone Marshall, the Dutchman was later seen leaving the stadium but wasn’t using any assistance.
Speaking to the press after the game, Amorim admitted he was worried about De Ligt’s most recent injury setback.
Amorim said: “I don’t know so I’m really concerned – not about Thursday. We took off Luke Shaw at half-time to protect and have players for Thursday, but I’m more concerned whether it is a small or big injury and thinking about next season.
“I don’t know. We will see. I hope it’s nothing serious. We took a risk with Maguire. Shaw had to go out because we need players for Thursday.”