Liverpool can take heart from a series of incredible European comebacks in their proud history when Barcelona visit Anfield for the second leg of the Champions League semi-final.

Barca hold a 3-0 lead from the opening match - thanks mostly to the enduring genius of Lionel Messi - while Liverpool's slim chances of reaching a second successive final have been further hit by a double injury blow.

After being restricted to a cameo appearance from the bench last week, Roberto Firmino's groin injury has ruled him out of the return, while Mohamed Salah is also unavailable due to a head injury sustained in the weekend win at Newcastle United.

It all points to a huge task facing Jurgen Klopp's side but if anyone can produce a European comeback for the ages, surely it is Liverpool. And Barca may be haunted by the memories of last season, too.

Omnisport takes a look back through the history books...

LIVERPOOL 4-3 DORTMUND [5-4 AGG], EUROPA LEAGUE QUARTER-FINAL, 2016

Klopp's 2016 return to former club Dortmund saw the teams draw 1-1, with few signs of the amazing drama that was to come in the second leg. Dortmund were 2-0 up inside nine minutes and although Divock Origi – a potential starter against Barca due to the absence of Salah and Firmino - reduced the deficit, Marco Reus then added a third away goal for the visitors. Liverpool's hopes of reaching the semi-final seemed over but Philippe Coutinho and Mamadou Sakho struck to level the tie at 3-3 on aggregate. The sensational comeback was completed in a breathtaking Anfield atmosphere by the unlikely figure of Dejan Lovren. "Everybody could see that something happened in the stadium, you could feel it, you could hear it, you could smell it," said Klopp afterwards.

LIVERPOOL 3-1 OLYMPIACOS, CHAMPIONS LEAGUE GROUP STAGE, 2004

Rafael Benitez's side were faltering in the early weeks of his first season at the club, having made a slow start in the Premier League and seemingly set to exit the Champions League at the group stage. Liverpool went into their final fixture needing to beat Olympiacos - and if the Greek giants scored the Reds would have to win by two clear goals to qualify. Rivaldo's opener, a fantastic free-kick, increased the size of the mountain Liverpool had to climb and they were still trailing at half-time. Benitez sent on Florent Sinama Pongolle and he grabbed one back, but Liverpool still needed to score twice. Neil Mellor put Liverpool in front in the game and who else but captain Steven Gerrard hammered home a sensational long-range strike to keep the Reds in the competition. Incredibly, though, there was even more drama to come for Liverpool in Europe that season...

AC MILAN 3-3 LIVERPOOL [AET], CHAMPIONS LEAGUE FINAL, 2005

Probably the greatest comeback in Champions League history, Liverpool came from 3-0 down at half-time against AC Milan in the miracle of Istanbul. Paolo Maldini's first-minute goal gave Milan the ideal start and a Hernan Crespo brace seemingly secured the trophy for the Rossoneri. However, Benitez's Reds had other ideas. "My concern was at half-time how to express what I wanted to say in English to make sure the team could understand," said the Spaniard.

Gerrard, whose all-action second-half performance defied description, cut the deficit to raise hope and Vladimir Smicer's long-range strike made it 3-2. Xabi Alonso astonishingly drew the scores level, tucking in the rebound after his penalty was saved. Milan should still have won it late in extra time, Jerzy Dudek somehow saving Andriy Shevchenko's point-blank effort, and the goalkeeper was Liverpool's hero when it came to penalties, keeping out attempts from both Andrea Pirlo and the Ukraine legend following Serginho's early miss, handing the Reds their fifth European crown.

ROMA 3-0 BARCELONA, CHAMPIONS LEAGUE QUARTER-FINAL, 2018

Rivalling Liverpool in Istanbul for the title of greatest Champions League fightback, Roma dumped out Barca in the Champions League quarter-finals in a result Messi and his side may recall ahead of their trip to Merseyside. Ernesto Valverde's side had won the first leg 4-1 at Camp Nou to put one foot in the last four of the competition, only to collapse in stunning fashion on Italian soil. 

Edin Dzeko struck in the sixth minute to give Roma some hope and the belief was flowing when long-term captain Daniele De Rossi converted a penalty to increase Barca's nerves. Roma's away goal from the first leg meant they knew one more would send them through, with their opponents dropping deeper and deeper in the closing stages and unable to fight back against the growing pressure. With eight minutes to go, Kostas Manolas completed the comeback to spark remarkable scenes of celebration at the Stadio Olimpico.