Atalanta stunned Anfield as Gianluca Scamacca scored twice in a 3-0 win on Thursday to leave Liverpool with a mountain to climb to reach the Europa League semi-finals.
Mario Pasalic added a third seven minutes from time to condemn Liverpool to a first home defeat in all competitions for 14 months.
The Reds had been favourites to end the Jurgen Klopp era by completing the German’s set of trophies won as Liverpool boss in his last game in charge in the Dublin final.
With Liverpool locked in a tight three-way battle for the Premier League title alongside Arsenal and Manchester City, Klopp showed that remains his priority as he made six changes to the side that were held 2-2 by Manchester United on Sunday.
Mohamed Salah was one of those left on the bench but he was unable to inspire a response despite being thrust into action right at the start of the second half after a lacklustre first 45 minutes from the home side.
Atalanta had won just two of their previous nine games in all competitions.
But the side sitting sixth in Serie A were a threat from the first whistle.
Pasalic missed a glorious chance to open the scoring after just three minutes when he fired into Caoimhin Kelleher’s face as the Irish international spread himself.
Harvey Elliott hit the crossbar and Darwin Nunez sliced wide when clean through on goal but those promising Liverpool attacks were few and far between.
Scamacca failed to shine during his one season in the Premier League with West Ham, but he has now scored three times in England for club and country this season.
Atalanta made the breakthrough on 38 minutes when the Italian international fired low through Kelleher’s grasp from Davide Zappacosta’s cross.
Teun Koopmeiners should have made it 2-0 before the break when he failed to beat Kelleher one-on-one.
Klopp reacted at half-time as Salah, Dominik Szoboszlai and Andy Robertson were sent on in a rescue mission.
However, even the changes failed to muster a response from a jaded looking side in their 50th game of the season.
Scamacca was offered an acre of space to slot home Charles De Ketelaere’s cross on the hour mark.
Luis Diaz and Diogo Jota were then introduced by Klopp but Liverpool continued to create little despite their abundance of attacking talent on the field and left themselves open to the counter-attack.
Atalanta took full advantage to close to within the brink of just their second ever European final.
Scamacca turned provider for the third after Szoboszlai gifted possession away inside his own half.
Ederson’s first effort was saved by Kelleher, but Pasalic thumped home the rebound to the delight of the travelling fans.
Liverpool have a history of thrilling comebacks in the European competition, most notably from 3-0 down at half-time in the 2005 Champions League final against AC Milan.
But they will need a fightback of that magnitude to keep alive the dream of sending Klopp out with a European trophy.
