Raphinha struck a dramatic winner in stoppage time as Barcelona came from behind to beat Benfica 5-4 in a wild match on Tuesday and virtually ensure direct qualification to the Champions League last 16.
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 late triumph in Lisbon.
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.
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 clash.