Liverpool snatched a late winner to beat Paris Saint-Germain away 1-0 in the first leg of their heavyweight Champions League last-16 tie, as Barcelona claimed a 1-0 win at Benfica despite the Catalan giants playing most of the game with 10 men.

French league leaders PSG dominated at the Parc des Princes but couldn't make their superiority count and Harvey Elliott struck three minutes from time after replacing Mohamed Salah with Liverpool's only shot on target.

Khvicha Kvaratskhelia had a goal ruled out for offside in the first half but Arne Slot's side defended resolutely to keep PSG at bay and are in a strong position to advance to the quarter-finals going into next week's second leg at Anfield.

Liverpool goalkeeper Alisson Becker made several crucial saves, as PSG had 28 attempts on goal but could not replicate the finishing that had allowed them to score 21 goals in their last five Champions League outings.

"It was probably the performance of my life," Alisson said.

"To go away with a win over here was probably a bit more than we deserved," added Slot.

If Liverpool finish the job at home next Tuesday, they could face Aston Villa in the quarter-finals, but PSG coach Luis Enrique said his side will have "nothing to lose".

"We deserved to win clearly, we created a lot of chances," said the Spaniard. "Football is unfair many times and you have to accept that."

Meanwhile, Raphinha drilled home after 61 minutes to give five-time winners Barcelona a slim advantage over Benfica despite playing most of the game with 10 men.

Teenage defender Pau Cubarsi was sent off midway through the first half of the tight clash in Lisbon with the score goalless.

Barcelona have not won the competition since 2015 but are expected to go deep this season, after a draw which many consider favourable.

Hansi Flick insisted before the game there was no such thing as an "easy" tie and the coach was proven right on a tense evening in the Portuguese capital.

"I said to the team that I'm very proud," said the German coach after his team emerged with a victory. "After the 22nd minute with 10 players it was not easy, and this is a big win."

Goalkeeper Wojciech Szczesny endured two high-profile mistakes against Benfica in the group stage in January, but made amends with a string of saves as Barca were pinned back in the final half hour.

Szczesny made a smart save to deny Benfica's Kerem Akturkoglu after just a few seconds, and the opening stages were played in a way that indicated both sides were picking up where they left off in Barcelona's wild 5-4 win in Lisbon.

Dani Olmo fired narrowly wide at the other end as Barca threatened, before Benfica goalkeeper Anatoliy Trubin produced a stunning triple save to keep the score level.

The Ukrainian first parried Dani Olmo's prodded effort, then made a brilliant reaction stop to thwart Robert Lewandowski converting from point-blank range and mopped up Lamine Yamal's attempt from the rebound. (AFP)