Atalanta came from behind to stun Chelsea with a 2-1 win in Bergamo thanks to Charles De Ketelaere’s late strike on Tuesday night.
The game’s first real chance fell to Ademola Lookman, who drilled in a low shot from the left, but Robert Sanchez’s leg kept the Nigerian out.
In the 19th minute, Josh Acheampong made a last-ditch block to deny Lookman, who was through on goal, to keep the score at bay.
Just before the half-hour mark, João Pedro broke the deadlock after Reece James played in a low cross for the Brazilian to tap home his first Champions League goal.
The goal was initially ruled out for offside on James, but after a lengthy VAR check, the goal was given.
The Blues resumed the break strong, and Jamie Gittens had his sights on goal, but his powerful strike was parried away by Marco Carnesecchi.
Minutes later, James could’ve doubled the visitors’ advantage after his initial effort was blocked, but his half-volley from the edge of the box was dragged wide.
Lookman thought he had drawn the host level after he stabbed himself a cross from the right, but the winger was miles offside.
La Dea mounted pressure on Chelsea’s defence and soon got the equaliser through Gianluca Scamacca after he headed home De Ketelaere’s cross at the back post.
The Italian’s effort from a free kick moments later was blocked and put behind for a corner.
Minutes after Alejandro Garnacho was introduced, he saw his curling effort fall straight into the gloves of Carnesecchi.
The Argentine appealed for a handball on Zappacosta in the area moments later, but the referee waved it away as the former Chelsea man’s arm was close to his body.
In the closing stages of the game, João Pedro saw his header float wide from the centre of the box.
At the other end, Krstovic was found with a long ball over the top, but his effort from a tight angle was blasted well off target.
In the 83rd minute, De Ketelaere broke free from a quick free-kick, and the Belgian drove at Marc Cucurella before unleashing a powerful shot past Sanchez.
The Blues sought for an equaliser late on as Garnacho struck a fierce shot, but Carnesecchi palmed his effort away.
With the final kick of the game, João Pedro saw his goal-bound effort saved, and the Blues returned home empty-handed.