Liverpool beat Lille 2-1 to maintain their perfect record in this season's Champions League and clinch qualification for the last 16, while Barcelona produced a stunning comeback to beat Benfica 5-4 in a classic to secure their own place.

The Anfield side are the only team with a maximum 21 points from seven matches in this new, expanded Champions League and they now know they will skip next month's play-offs and head straight to the last 16 in March.

Mohamed Salah ran clear to give Liverpool the lead at home to a Lille team who have also impressed this season, and the visitors appeared in trouble when they had Aissa Mandi sent off just before the hour mark.

Jonathan David swept in an equaliser for Lille, but Harvey Elliott's shot took a wicked deflection on its way in to give Liverpool the points.

"We're happy that we are top eight. That's the only thing that tells me something, because this league table doesn't tell you anything," said Slot when asked about being through to the last 16.

But the biggest drama on the night, however, came in the rain in Lisbon, where Barcelona trailed 4-2 with 12 minutes of the 90 remaining, but somehow recovered to win 5-4.

Greek striker Vangelis Pavlidis scored a hat-trick in the first half-hour for Benfica, including a penalty, while Robert Lewandowski netted from the spot for Barca, who were 3-1 down at the interval.

Raphinha pulled it back to 3-2 when a clearance by the goalkeeper ricocheted back off the Brazilian's head and in, but a Ronald Araujo own goal midway through the second half appeared to have secured the win for the Portuguese side.

However, another Lewandowski penalty on 78 minutes gave Barcelona renewed hope, and Eric Garcia headed in the equaliser on 86 minutes, before Raphinha ran away to settle an incredible game.

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

The Catalans are second with six wins out of seven, and will finish in the top eight to go straight to the last 16. Benfica, with 10 points, must still sweat to reach the play-off round.

Elsewhere, Atlético Madrid are third on 15 points and certain to at least be in the play-offs after a Julián Alvarez brace secured a 2-1 home victory over Bayer Leverkusen in a game both teams finished with 10 men.

Atletico had Pablo Barrios sent off midway through the first half, and Piero Hincapie then put Leverkusen ahead just before the break.

Argentina star Alvarez levelled seven minutes into the second half, and Hincapie was sent off for the Germans before another Alvarez goal won it for the home side in the last minute as they climbed above Leverkusen.

Last season's Europa League winners Atalanta are also guaranteed at least a play-off place after crushing Sturm Graz of Austria 5-0. (AFP)