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.
Jurgen Klopp insisted that he is completely focused on his job as Liverpool manager amid rumours linking him to Bayern Munich.
Franz Beckenbauer had recently shared his opinion on how the German would make an idea coach at Bayern.
Klopp dismissed these comments and emphasised the fact he is committed to his job as Liverpool boss.
“I have a contract at Liverpool until 2022. And nobody here has the feeling that we should cancel it,” he told Welt.
“Neither from the owners nor from my side there is even a tendency in this direction. So, nobody has to think about that.
“Franz just says such a sentence and, of course, he triggers very much with it. He didn’t ever care about that.”
The former Borussia Dortmund coach admitted that he has not thought about life after Liverpool but he does see himself at the Merseyside club for a long time.
“It’s long way until then,” he added. “In principle in football it’s like that – the opportunity and the timing have to be right.
“But I’m totally happy here and I don’t feel I’m any kind of finished at all. Our team has a good age structure, we can still work together for a long time.”
However, the fact Jurgen Klopp’s men top the Premier League in their quest to end a 29-year wait to win the title and face Porto in the first leg of a Champions League quarter-final at Anfield on Tuesday, is largely thanks to Mane.
As Salah’s goals dried up in an eight-game drought prior to Friday’s 3-1 win at Southampton, Mane assumed the mantle as chief goal getter with 11 in his last 13 Liverpool appearances taking his tally for the season to 20.
That run included a double away to Bayern Munich last month that eased the five-time European champions past the German giants and eyeing another shot at Champions League glory.
His first goal in particular at the Allianz Arena was a demonstration in the 26-year-old’s pace, skill and calmness in front of goal.
Mane controlled a raking long pass from Virgil van Dijk, rounded Manuel Neuer and then dinked the ball into an unguarded net.
“I’m going to have to watch back 500 times,” admitted Klopp after the game. “It’s astounding what he did.”
Mane scored 10 Champions League goals in all last season, including in the final.
However, his brave header in Kiev to bring Liverpool briefly level was quickly forgotten amid the furore over Salah’s early shoulder injury that saw him hobble off and aided Real Madrid’s route to a third straight European title.
While Salah now carries himself with a swagger from the star status he has earned over the past two years, Mane’s humble nature means he often remains under the radar for a player of his quality.
In September he was filmed helping to clean the toilets at his local mosque just hours after scoring in a vital away win at Leicester.
Last week in an internal interview with Liverpool’s club media, he detailed a daily routine that consists of healthy eating, prayer and early nights.
“That’s how a normal day for me looks. This is my dream, this is something I’ve always wanted to do, and I am so grateful that I am able to do it now,” he said.
“My dream came true, to play for one of the biggest clubs in Europe with a great team, a great manager.”
Porto are already very aware of the threat Mane poses. When the sides met in the last of the Champions League last season, he scored a hat-trick in a 5-0 first leg rout in northern Portugal that killed the tie as a contest even before it even returned to fortress Anfield.
This time round, Liverpool will be keen to get the job done in the first leg on home soil.
Klopp’s men have not made life easy for themselves in recent weeks on league duty, requiring late goals to see off Fulham, Tottenham and Southampton to keep their title dreams alive.
However, just by keeping pace with quadruple chasing Manchester City all season, they have shown a maturity and mental strength that has evolved from the kamikaze matches that carried them to last season’s final.
“The boys are mentality monsters – I love that,” said Klopp after victory at Southampton.
Moreover, unlike when Sergio Ramos’s takedown of Salah seemed to suck belief from Liverpool against Madrid almost a year ago, they now have a cast of characters capable of stepping up.
Goalkeeper Alisson Becker and talismanic centre-back Van Dijk have strengthened the defence.
And, at the other end, Mane has shown he can be counted on at the business end of the season.