Benfica were leading 4-2 with under 15 minutes remaining but Barcelona mounted a stunning late comeback to stay three points behind leaders Liverpool.

Vangelis Pavlidis hit a first-half hat-trick for the hosts, in part thanks to two big errors by Barcelona goalkeeper Wojciech Szczesny.

However a Robert Lewandowski double from the penalty spot, Eric Garcia's header and a brace for Raphinha helped Barcelona claim a stunning last-gasp triumph in Lisbon.

"It was a crazy game... Benfica did well in the first half but we made a lot of mistakes," said Barcelona coach Flick.

Barca showed grit to keep fighting after going in 3-1 down at half-time and swiftly conceding again after Raphinha pulled one back.

"The mentality of the team, they always believe in themselves and this was unbelievable to see," said Flick.

"In the second half we created more chances than them and we deserved it."

Benfica opened the scoring in the second minute, when Pavlidis escaped Pau Cubarsi and fired home from Alvaro Carreras' low cross.

Barcelona responded swiftly with Lewandowski scoring from the penalty spot after Alejandro Balde was brought down by Benfica defender Tomas Araujo.

The hosts nosed back ahead through a stroke of luck, when Szczesny raced out of his goal to try and cut out a through-ball, but crashed into Balde.

Greece international Pavlidis gleefully collected the loose ball and rolled his second into the empty net.

Barcelona, who lured Szczesny out of retirement to replace the injured Marc-Andre ter Stegen in October, soon fell further behind.

Pavlidis completed his half-hour hat-trick with a penalty after another Szczesny mistake, with the goalkeeper flying in to try and dispossess Kerem Akturkoglu but bringing him down.

Barca battle back 

Lamine Yamal and Raphinha missed good chances before the break as Barcelona pushed forward.

Benfica goalkeeper Anatoliy Trubin saved from Jules Kounde, who should have scored, and Lewandowski could not turn home from Pedri's dangerous ball across the face of goal.

Raphinha pulled one back for Barcelona in bizarre fashion as a clearance by Trubin struck his head on the edge of the area and flew back into the net.

However, Benfica soon struck again, with Ronald Araujo nudging past Szczesny into his own net as he tried to cut out a cross.

Barcelona kept pushing and Lewandowski converted another penalty after Nicolas Otamendi brought down Yamal.

The Catalan giants, who last won the Champions League in 2015, pulled level when substitute Garcia headed home from Pedri's inviting cross.

Szczesny saved former Real Madrid star Angel Di Maria's low shot before Raphinha's dramatic winner.

With Benfica appealing for a penalty, Barcelona sprang a quick breakaway and the Brazilian winger slotted home to end a blockbuster battle.

Players from both sides clashed after the final whistle as tempers flared following the thrilling denouement.

"We knew how hard it would be here, in front of their fans, and they know how to play really well, they have top level players," Raphinha told Movistar.

"We didn't let ourselves sink at 3-1 down, we were focussed on what we needed to do to try and change the game.

"It was a spectacular game for everyone. They could have won, or us, but we managed to take it."