Klopp’s gamble in making six changes to his Liverpool line-up backfired as West Ham misfit Gianluca Scamacca struck in each half – the first resulting from a bad error by goalkeeper Caoimhin Kelleher.

With the Anfield atmosphere less colourful than usual as part of a fans’ protest, the Europa League favourites struggled forcing Klopp to make a triple change at half-time – including the introduction of Mo Salah.

By then, Atalanta led when Scamacca’s speculative strike squirmed under the body of Kelleher. And the big Italian, who was part of West Ham’s Europa Conference-winning campaign last season, extended the visitor’s lead with a cute first-time finish after an hour.

Liverpool’s task of clawing back a first-leg deficit was then made much harder when Mario Pasalic added a late third – putting Klopp’s dream of a winning farewell in a Dublin final at more than serious risk.

Though the Europa League is not the glossiest title Jurgen Klopp is going for this season, the Liverpool manager has a sentimental connection with the competition, citing his run to the final in 2016 as the first step towards his success at Anfield.

He made wholesale alterations last night with the Premier League title race in mind, with Mo Salah among those on the substitutes bench, where he was joined by Trent Alexander-Arnold and Diogo Jota following a couple of months out with injury.

Absent altogether were the customary flags on the Kop, a protest from fans against the club raising season ticket prices for next season.

The only banner displayed was No To Ticket Price Increases in red letters on a white background and that was removed before the first whistle in accordance with Klopp’s wishes that the protest shouldn’t be a distraction during gametime.

Atalanta are sixth in Serie A and beat Liverpool at Anfield in a Champions League game in 2020 under their current manager, Gian Gasperini.

But despite their squad including familiar names to Premier League fans including Ademola Lookman (ex-Everton), Marten de Roon (Middlesbrough), David Zappacosta (Chelsea) and Gianluca Scamacca (West Ham), Liverpool started the two-legged quarter-final as clear favourites.

Even so, it was the visitors who created and squandered the first chance in bizarre circumstances after three minutes.

Harvey Elliott lost out to de Roon and Mario Pasalic looked certain to score from six yards. He struck the ball well enough but a diving Caoimhin Keller blocked the ball with his cheek to divert for a corner, leaving the Irishman with a mark on his face.

Roused from a slow start, Darwin Nunez quickly tested Juan Musso at the other end. But Atalanta showed their attacking teeth when full-back Zappacosta bombed forward and squared for Charles De Ketelaere.

Instead of shooting, the Belgian forward backheeled for Teun Koopmeiners whose shot was blocked.

Nunez was criticised on Sunday for missing a good chance that could have wrapped up the points at Old Trafford.

Unfortunately for the Uruguayan striker, he was wayward again after 16 minutes. After making a good run to beat the offside trap and collect a pass from Curtis Jones, he got his angles wrong and chipped wide by a distance.

Even so, Nunez is a constant nuisance for defenders and the foul on him by Isak Hien earned the Atalanta defender a booking.

When the resulting free-kick ended up at Harvey Elliott’s feet on the right-edge of the penalty area, his curler hit the bar and then deflected onto the post, a case of the youngster being doubly unlucky.

Liverpool couldn’t build momentum from the near-miss and after 35 minutes, Klopp sent four of his substitutes including Luis Diaz, Diogo Jota and Dominik Szoboszlai to warm up, hoping it would spark those on the pitch into decisive action.

It had the opposite effect with Atalanta taking the lead after 38 minutes. Again, Zappacosta was the attacking outlet, running towards the Liverpool byline and picking out Scamacca with a cutback.

The big Italian’s low first-time strike from 12 yards should have saved to Kelleher’s left but squeezed agonisingly underneath the keeper’s flailing arm and rolled over the line.

Scamacca is something of a European specialist. Although he scored only eight goals in a disappointing season at West Ham last year, five were in their winning Europa Conference campaign before he missed the final through injury.

Kelleher went some way to redeeming himself almost immediately, coming out sharply at the end of the first half to narrow the angle and block Koopmeiners when the Dutchman had raced clear. But it was still an important half-time team talk from Klopp with Liverpool trailing.

He also made three changes at the interval with Salah, Szoboszlai and Andy Robertson replacing Elliott, Kostas Tsimikas and Curtis Jones, giving Liverpool a far more first-team look though Jones did well on the comeback trail after injury.

Liverpool immediately upped the tempo with Virgil van Dijk and Szoboszlai having efforts. Salah’s first sight of goal after 55 minutes led to Juan Musso tipping around the post.

Nunez lifted a chance over the bar from eight yards with Klopp coming out to the edge of the pitch to encourage his charges. It was the centre-forward’s last action however, replaced by Diaz, but the Colombian hadn’t even touched the ball when Atalanta scored again.

The Italians played through the lines until De Keletaere squared from the right and Scamacca sidefooted first-time into the corner well beyond Kelleher’s reach.

After 75 minutes, Klopp made his last change – Diogo Jota coming on for his first start since a knee injury on February 17.

The only consolation on a disappointing evening for Klopp is that in their Champions League double-header four years ago, Atalanta won 2-0 at Anfield – and The Reds won 5-0 in Italy.

But their task was made much harder after 82 minute when Szoboszlai gave the ball away allowing de Roon to have a shot that Kelleher parried and Mario Pasalic tucked away the rebound.