The Manchester United goalkeeper made a huge error to allow the Italian side to go ahead on Tuesday night.
Atalanta brought the ball out from the back and Duvan Zapata was played in behind, with the striker keeping his cool and crossing for Josip Ilicic to hit a low, first-time strike.
The ball somehow squirmed underneath goalkeeper David De Gea to pile more pressure under United and Ole Gunnar Solskjaer.
The goal would have been particularly satisfying for Ilicic as he is a huge Liverpool fan.
He loves the club so much he has an incredible tattoo paying tribute to the Premier League giants.
This summer, he unveiled the new ink that showed him touching the famous 'This Is Anfield' sign at the club's famous ground.
The forward has not fully explained his love of Liverpool, but it must be pretty serious to get a permanent memento on his body.
De Gea, though, should have done much better for the goal.
talkSPORT commentator Andy Townsend said: "I'm expecting the goalkeeper to save that. Ole Gunnar Solskjaer will be looking at his bench to say 'why hasn't he saved that there'."
Cristiano Ronaldo did manage to get his side back onto level terms just before half-time.
Duvan Zapata thought he had scored the winner for Atalanta before Ronaldo bailed out the Red Devils once again as the game ended 2-2.