With a defeat in November, Liverpool’s December just got a whole lot trickier.
Revenge was sweet for the Italians. Beaten 5-0 in Bergamo three weeks ago, Gian Piero Gasperini’s side got their own back on Merseyside, inflicting a 2-0 defeat which keeps Group D wide open, for now at least.
Victory here would have seen Jurgen Klopp’s men through to the knockout stages with two games to spare. Instead, with Ajax beating Midtjylland in Amsterdam, Liverpool now need a result when the Eredivisie side visit next week to guarantee qualification.
A defeat would leave them vulnerable, needing something from their final group match, as they have in each of the last three campaigns.
It means Klopp, his resources already stretched by injury, will have less room to comfortably rotate his squad during the busiest month of the campaign.
Liverpool play 10 times between November 28 and January 2, and as it stands none of those games will be free hits for the Premier League champions.
Klopp chose to make changes here. Five of them, in fact, from Sunday’s impressive win over Leicester City.
There were chances for the Williamses, teenagers Neco and Rhys, and opportunities for Kostas Tsimikas and Divock Origi, as well as a return for Mohamed Salah.
The result, though, was a disjointed performance which got what it deserved. Liverpool were second best for large parts, created little offensively and eventually succumbed to two goals in four second-half minutes, courtesy of Josip Ilicic and Robin Gosens.
Klopp cut a frustrated figure on the touchline, unhappy with most of what he saw.
Tsimikas, making only his second competitive appearance, got plenty of earache, as did Origi, whose form continues to underwhelm. The Belgian is doing little to push for greater inclusion, at present.
It took 43 minutes for Liverpool to muster even a shot, and when it came Salah blasted it well off target. The home side struggled to string any moves of note together, their rhythm lacking against a team that clearly learned their lessons from the first game.
Liverpool had looked to change the game off the bench in the final half hour, but as Klopp readied four substitutes – Andy Robertson, Fabinho, Diogo Jota and Roberto Firmino – Atalanta struck.
Ilicic and Papu Gomez had been the main threats for the Italians, and it was they who combined, with Gomez’s cross slid home by the Slovenia star at the far post, with the Reds backline sleeping.
It got worse moments later, as another Gomez delivery saw Robertson beaten in the air by Hans Hateboer, with Gosens on hand to slot home his side’s second.
There was to be no response from the home team, who ended the night without a single effort on target. Second best, for once, on their own soil.
The damage need not be too bad. Liverpool should have enough to get what they need against Ajax (or Midtjylland), but it will frustrate Klopp that having taken an understandable gamble with his selection, his replacements were unable to deliver.
This was the heaviest home defeat Klopp has suffered as Reds boss - the last time they lost by more than one goal at Anfield came under Brendan Rodgers, a 3-0 reverse at the hands of West Ham in August 2015.
He will hope for better news from the treatment room this week, with Jordan Henderson and Alex Oxlade-Chamberlain stepping up their rehab. Maybe, too, we will see Thiago Alcantara on the field again soon. It has been a long enough wait.
They head to Brighton on Saturday – an early kick-off, in case you missed Klopp’s latest broadside against the broadcasters – and we can expect a more familiar team at the Amex Stadium, with crucial league points on the line.
A more familiar team, and a more familiar performance, Klopp will hope.
This was Liverpool, but not as we know them.