Holding Manchester City to a 1-1 draw in the group stage that season, Atalanta went on to reach the Champions League quarter-finals, narrowly losing out to Paris St-Germain. A few months later, they defeated Liverpool at Anfield.

Under Gian Piero Gasperini, Atalanta's brand of intoxicating football combined beauty with industry. It galvanised the neutrals, inspired a generation of tacticians and gained a legion of new fans - all on a shoestring budget.

It is remarkable a team whose sole objective was once Serie A survival has evolved into seasoned challengers, and European competition regulars.

This is despite the fact the club continue to sell off their best assets to balance the books and turn a profit. It was Rasmus Hojlund last year and it will probably be Teun Koopmeiners (linked with Liverpool and Manchester United among others) at the end of this season.

Atalanta can always be trusted to unearth great young players that they develop into fine specialists. How do they do it?

"The Atalanta model is very simple: people who work from morning to night and a fanbase and a city that live for the club and the team. Basically, there is passion and work 24 hours a day, 365 days a year," explained former technical director Giovanni Sartori.

Atalanta are a labour of love. Only those capable of putting in the hard work will be scouted and invited.

"During training, my players need to struggle; those who aren't used to working hard scare me. But from the struggle, victories are born," explained Gasperini in an interview with Fabrizio Romano.

Having Gasperini as coach has helped the club sustain this model - allowing them to challenge the bigger clubs in Italy and Europe despite operating on a smaller budget. They spend approximately 44m euros annually on total salaries. Juventus spend nearly triple that.

A genius with a clear philosophy, Gasperini has many admirers, including Bologna coach Thiago Motta, who played for him at Genoa, and Brighton's Roberto de Zerbi. Jurgen Klopp recently described the Italian as a super coach and Atalanta as "very uncomfortable to play against".

Atalanta are famed for a man-marking style of play and a desire to engage in duels. Intense and ferocious, they attempt to destroy the opponent's gameplan and organisation to create one on ones across the pitch.

Always hunting for possession, they switch play with ease, pull players wide to open central passing lanes and progress the ball quickly to create goalscoring opportunities.

'Genius' Gian Piero Gasperini was appointed Atalanta manager in the summer of 2016

Dynamic in their approach, Atalanta are Serie A's fourth-highest goalscorers and yet it's fair to say they haven't always convinced going forward, at least not when compared to previous seasons.

It hasn't helped that striker El Bilal Toure, their record signing, needed thigh surgery last August, and did not make his first appearance of the season until February.

With an array of attacking talent, Gasperini has attempted to find the right combination for success. The truth is, they are missing the technique and individual quality they possessed the last time they visited Anfield.

They miss the skill and intelligence of Josip Ilicic, who returned to his native Slovenia to join Maribor two years ago, and have never quite replaced the genius of Papu Gomez, a player who roamed the pitch to create, score and elevate their style of play. This current version of Atalanta, while still very good, is more bark than bite at times, more anger than thoughtful precision.

Atalanta are opportunistic - they will make the most of indecision and pounce on errors. They have the stamina to keep fighting but not always the technique or the calm presence of mind to carve open opponents.

Gasperini is forever focused on making tactical adjustments to place his players in their best positions but at times it has proved hard to overcome opponents who can counter his ideas.

Their brand of football is both physically and emotionally exhausting - and with injuries and absences having an impact, Gasperini has struggled to rotate the squad well enough to ensure players are rested and capable of continued dominant performances.

Atalanta have been exposed in recent weeks by the demands of challenging in the Coppa Italia, Europa League and attempting to finish in Serie A's top five. They don't have the depth of squad to fight on all fronts and could potentially miss all their campaign targets.

After a thrilling 3-0 win against Napoli, they seem to have run out of energy, suffering two defeats in a row. The match against Cagliari on Sunday looked very winnable, but wily tactician Claudio Ranieri had other ideas.

Cagliari showed focus and fight and, with Ranieri's adjustments and substitutions working, they came from 1-0 down to win 2-1. Gasperini walked away ruing his side's inability to match Cagliari's spirit and motivation.

The best way to play Atalanta is to show courage. Aggressive in nature and determined to win back possession, the lower they are forced to go back, the less likely they are to hurt. Defensively they have managed an impressive number of clean sheets in Serie A but they remain vulnerable on set-pieces and against dynamic, direct play.

Offered the chance to take on Europe's finest again as they face Liverpool, Atalanta are desperate to avoid a third defeat in a row.

In Koopmeiners, they have a remarkable talent who is capable of goals and relentless intelligent movement, while Aleksej Miranchuk provides the technique and unpredictability required to lift their attacking game.

On their day, Atalanta can beat anyone. They just haven't had one of those days in a while.