VIDEO Liverpool 4-3 Borussia Dortmund: Highlights; Stunning Reds Comeback Secures Europa League Semifinal Berth

Dejan Lovren, Liverpool vs Borussia Dortmund — Liverpool celebrate Dejan Lovren's dramatic winner against Borussia Dortmund in the Europa League quarterfinals. Getty Images

Liverpool produced a sensational fightback to reach the Europa League semifinals after an unforgettable 4-3 win over Borussia Dortmund in a breathless second leg at Anfield. Having twice needed three goals to progress, Liverpool never gave up hope and secured a remarkable 5-4 aggregate triumph when Dejan Lovren headed an injury-time winner.

Jurgen Klopp’s side appeared out for the count after Dortmund began the contest in scintillating fashion and scored twice in the first nine minutes through Henrikh Mkhitaryan and Pierre-Emerick Aubameyang. Liverpool gave themselves hope when Divock Origi poked home early in the second half, but again they were left needing to score three times after Marco Reus pounced soon after.

Again, though, Liverpool, roared on by the Anfield crowd and a fully charged Klopp on the sidelines, refused to go down quietly. Philippe Coutinho curled home a wonderful strike, before Mamadou Sakho headed home a corner to ensure a pulsating final 12 minutes.

Still, with the last seconds of regulation time having ticked away it appeared that Liverpool's considerable efforts would be in vain. That was until, just moments after the board for four minutes of injury time came up, Dortmund were caught out by a free-kick and James Milner crossed deep into the box, where Lovren rose highest to etch his name into Anfield folklore.

That Lovren and Sakho, two players who have been much maligned during their Anfield careers, would prove the heroes was something nobody could have foreseen. But then the same is true for so much of what transpired on Thursday night.

It had begun with a spine-tingling rendition of “You’ll Never Walk Alone” from both sets of fans and an impeccably observed minute’s silence on the eve of the anniversary of the Hillsborough disaster. There was no question that the Liverpool fans, buoyed by their strong showing and a 1-1 draw in the first leg against the favorites for the competition, were fired up in anticipation of what they hoped would be another famous European night at Anfield.

But all that that anticipation was punctured inside nine minutes. Dortmund had been subdued on Klopp’s return to the Westfalenstadion a week ago, but early on at Anfield they showed why under Thomas Tuchel this season they are regarded as one of the best teams in Europe.

Twice the visitors won the ball back in their own half and stormed forward with scintillating pace and brilliant precision to leave Liverpool horribly exposed. After Mkhitaryan finished off following Simon Mignolet’s save from Aubamayang, the Gabon striker slammed the ball high into the net for his side’s second.

At times Liverpool were simply outclassed by their opponents, something which would be no disgrace in Klopp’s first season in charge. Yet, surely helped by Klopp’s infectious spirit, Liverpool always offered some belief that they could overcome their obvious handicaps in pure talent and avoid Dortmund simply coasting to victory.

There was no problem for Liverpool creating chances in the first half, but their failure to take any looked likely to prove costly. A goal early in the second half was surely required, and they got just that when Origi fed onto Emre Can’s through ball to continue his recent prolific streak and growing emergence into a high-class striker.

Klopp’s mood soon turned to furious frustration, however. Nathaniel Clyne was caught dozing to allow Reus to run in behind him and place a shot expertly into the far corner of the net. Liverpool needed three goals once more and some swift inspiration. As so often, Coutinho provided it, linking up with Milner just outside the box before curling sublimely into the bottom corner of the net.

Sakho’s role to that point had been playing Dortmund onside for all three goals. It looked set to be just another contest which reinforced Liverpool’s need to upgrade at the back if they are to truly match the likes of Dortmund on a regular basis. Instead, the center-back was on hand to stoop and make it truly game on for the first time in the 78th minute.

It may only be the Europa League, but what followed from Sakho’s center-back partner, Lovren, provides plenty of reason for optimism that Klopp will soon have Liverpool back at the top table in Europe. And this victory means that the Merseysiders have kept their hopes very much alive of a return to the Champions League arriving as soon as next season.