Having overcome the same visitors 5-0 on aggregate last season in the last 16, it was another comfortable victory.
The Reds got the perfect start in the fifth minute when James Milner swung out a ball to Sadio Mane on the left.
He found Roberto Firmino in support and he teed up Keita – who scored at Southampton last Friday – for a shot which was deflected in by the sliding Oliver Torres.
Mohamed Salah should have added a second, driving a volley straight at Iker Casillas, before rolling a finish agonisingly wide.
It was Firmino who did extend the lead in the 26th minute when he calmly netted from a right-wing cross by Trent Alexander-Arnold.
Porto did press and their best opportunity saw Alisson block Moussa Marega’s shot.
DREAMING OF THE DOUBLE
While all the talk is of Manchester City’s pursuit of history and a potential quadruple, or quintuple if you count the Community Shield, it would be foolish to dismiss Liverpool’s strong claims for a dream double.
The Premier League title race is by no means over. City are two points behind with a game in hand, but have the tougher run-in and far greater pressure.
And, as they showed here in convincing fashion and taking a massive step into the Champions League semi finals, Jurgen Klopp’s men have the belief and bravado to win both competitions.
They also have the quality and squad depth to do it too.
Even the loss of the reliable Andrew Robertson, missing through suspension, made little difference against a Porto side lacking the same ruthless approach.
Up stepped James Milner to produce another steady display even if it was on his unfavoured left-hand side.
Then there was Dejan Lovren, who last started in the FA Cup loss at Wolves in January, but offered a physical presence on his return.
And Naby Keita displayed the sort of energised performance that prompted Liverpool to spend £52 million on him.
It has been a season where he has struggled and there were doubts, but the Guinea international is now coming to the fore at just the right time. He waited eight months for a goal, but now has two within a week.
But Keita hustled and bustled well in a midfield that was composed as well as committed with Fabinho and Jordan Henderson showing good support.
With Sunday’s crunch game with Chelsea to follow, this Reds side has shown a lot of guts in a tough campaign. Now it could finally be time for glory.
He may not have got the plaudits or acclaim afforded to Salah or Sadio Mane, but there is no doubting the value of Roberto Firmino.
With clever movement, deceptive pace, a deft touch and subtle finish, the Brazilian has the ability to bemuse any defence.
He scored one, starting the move himself, and assisted another and was a constant threat against the Portuguese visitors.
Firmino is an all-round striker in the mould of say Sergio Aguero in the way he can drift across the frontline, hold up play and drop into midfield to create when possession is lacking.
He may not possess Aguero’s predatory skills in the box, but Liverpool do not play in the same manner as City.
While much attention and focus is often on Salah and Mane, Firmino has taken advantage to become Liverpool’s silent assassin.
His creative contributions will be crucial in this run-in and beyond. He is a player still improving and becoming increasingly effective.
PREPARE FOR PORTO EXODUS
It says a lot for Porto when Eder Militao is heading for Real Madrid after just one season.
There is much excitement about the potential of the Brazilian centre-back, who cost the Spanish giants €50 million.
At 21, he will learn from nights like this as the Liverpool frontline caused him and his defensive team-mates all sorts of problems.
Militao’s departure is unlikely to be the last as Porto do not look good enough to ever go beyond this stage in Europe.
Their most talented individuals will want to test themselves higher and Moussa Marega should be on the radar of Premier League and Bundesliga clubs.
The striker came close to joining Ruud van Nistelrooy, Edinson Cavani and Cristiano Ronaldo in scoring in seven successive Champions League matches, denied only by a fine block from Alisson.
But with pace, power and some work, he could be a beast in a better side.
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