Mane opened the scoring when home goalkeeper Jose Sa failed to hold his placed strike.

Mohamed Salah then showed wonderful composure to steer the ball home for Liverpool's second and his 30th of an incredible debut season at the club.

With two away goals scored, the visitors could have been forgiven for taking a more conservative approach but instead they went for more.

A swift Liverpool counter-attack ended with Sa spilling Roberto Firmino's shot into Mane's path and the striker made no mistake, before Firmino scored his 21st of the season, sweeping home James Milner's cross.

Mane got his third with a driven strike late on to become the first Liverpool player to score a hat-trick away from home in Europe since Michael Owen in 2002, and the second ever.

Porto had lost only two matches in all competitions this season prior to Wednesday's game but simply could not cope with Liverpool's unstoppable forward line.

Otavio had the Portuguese side's best chance towards the end of the first half, placing his shot just wide of the far post after he was put through on goal.

Liverpool will expect to complete the job when they host Porto in the return leg at Anfield on Tuesday, 6 March.

Like they were never away
Liverpool boast a proud record in continental football having won the European Cup or Champions League five times - more than any other English side.

But this was their first involvement in the knockout stages of the competition since 2009, when they lost 7-5 on aggregate to Chelsea in the quarter-finals.

And it was like they had never been away as they made light work of a side that reached this stage of the competition last season and were quarter-finalists just three years ago.

Only PSG (25) scored more goals than Liverpool (23) in the Champions League group stages and the Reds picked up where they had left off in December as their front three proved too much for a nervous Porto defence.

The hosts ultimately became the latest side unable to cope with Liverpool's pace on the counter-attack. This was the 17th time Liverpool had scored three goals or more in a game this season and the 10th time they have done it away from home.

They have also now scored more Champions League goals this season (28) than any other club and, on this evidence, are going to take some stopping in the competition.

Superb Salah on course for 40 in a season?
Games without Salah on the scoresheet this season have been rare. Indeed, the former Chelsea forward's longest 'drought' was a run of three without scoring towards the end of last year.

The forward is on a quite incredible run of goalscoring form that shows no sign of slowing down. His goal against Porto was his sixth in five games and took his total for the campaign in all competitions to 30 - only 12 players have managed that in Liverpool's history.

Salah has produced some quite sensational strikes this season and while his goal against Porto was, in the end, a tap-in, such a description hardly does justice to the amazing coolness he showed in the build-up to the finish.

After Milner's shot from distance bounced back off the post, Salah took one touch to lift the rebound beyond the reach of the goalkeeper, cushioned the ball on to his left foot with a calm header and slotted the ball home between a defender and the keeper.

It was more stunning artistry from the Egypt international and, given that it is only mid-February, it is not unreasonable to expect that he could surpass the 40-goal mark by the end of the season.