It could certainly have been more, but the Reds will take a two-goal advantage into Wednesday 13th April’s Anfield second leg.
A superb first-half showing at Estádio da Luz saw them go into a 2-0 lead and create several chances on top of their goals.
Those came through Konaté’s first for the club – a 17th-minute header from an Andy Robertson corner – and Mané’s 34th-minute close-range finish after Díaz coolly nodded Trent Alexander-Arnold’s sublime diagonal pass into the Senegalese’s path.
Núñez – who led the line with consistent vigour for the hosts – halved the deficit in the 49th minute when a Konaté misjudgement allowed him to control Rafa Silva’s cross and convert, but the two-goal cushion would be restored late on.
Having had to weather some good spells of Benfica pressure, the visitors began to look increasingly dangerous as the minutes ticked down.
Which culminated in the excellent Naby Keïta making a key 87th-minute interception before he slid Díaz through.
The Colombian – who arrived at Anfield in January from Benfica’s Portuguese rivals FC Porto, of course – rounded goalkeeper Odysseas Vlachodimos and slotted home to complete the night’s scoring.
A good foundation for next Wednesday’s return match on Merseyside – where Liverpool will hope to secure a semi-final place – and an encouraging way to precede Sunday’s Premier League trip to title rivals Manchester City.
Contrasting halves
There were chances aplenty for Klopp’s side here. Particularly in the first 45, they consistently created openings – and in various ways.
A pleasing mix of well-used turnovers, intricate passing, well-timed crosses and dangerous set-pieces were behind the opportunities.
It should, in truth, have been more than three. But three goals away from home in Europe is certainly not to be sniffed at – and plenty of credit ought to go to Benfica goalkeeper Vlachodimos, who made five saves over the course of the contest.
Four of those five came within one-on-one situations – the last of which saw Diogo Jota denied in the seventh minute of second-half stoppage time.
That – aside from Díaz’s goal – was about as clear a chance as the visitors created after the break, though.
They had to see out some good spells of pressure from the home side after Núñez’s goal four minutes after the restart.
Alisson Becker was forced into a good save by Everton’s low 18-yard attempt in the 60th minute, but that was about as close as the Primeira Liga outfit came to equalising.
Liverpool’s increasingly honed European nous was, in a sense, more clearly on display in the second half – as they steadied the ship, saw things out and struck late – than when they were dominating in the first.
Things could still have been managed better, in places, but this was a side again displaying a pleasing range of dimensions.
Díaz, Keïta and full-backs impress
It felt like every player involved for Klopp’s side played a genuinely notable role in Tuesday’s win.
Mohamed Salah, for instance, may have had another somewhat frustrating outing, but he was a constant threat in behind and elsewhere, prior to his 61st-minute substitution.
The contributions of the likes of Díaz, Keïta, and full-backs Alexander-Arnold and Robertson felt especially evident, however.
Robertson’s outswinging corner was superbly inviting and got the finish it deserved from Konaté to open the scoring.
The Scotland captain was familiarly dynamic and proactive down that left flank, while Alexander-Arnold was similarly impactful down the right.
Making his first appearance since recovering from the hamstring issue that had kept him out since mid-March’s 2-0 success at Arsenal, the 23-year-old offered several reminders of his exceptional vision and range of passing from right-back.
That was most evident in the 34th minute, when his superbly flighted diagonal ball found Díaz’s dart into the box in the inside-left channel.
The 25-year-old forward hardly had to break stride before unselfishly heading the ball into the path of Mané, who duly slotted into the gaping net.
And Díaz got a well-earned goal of his own late on. He displayed brilliant pace, substantial composure and adept finishing to race onto Keïta’s deflected pass, evade the in-form goalkeeper and find the net with his weaker left foot before defenders could get back onto the goal line.
Keïta had been an energetic, positively aggressive and creative presence for much of the evening – and this assist, following a key interception, therefore felt a somewhat apt way to conclude his display.
It was especially pleasing given this came almost exactly a year after he was substituted in just the 42nd minute of last season’s 3-1 quarter-final first-leg loss at Real Madrid.
Momentum has rarely been easy to come by for the Guinea skipper, but this felt like another hint at headway on his part.
That three of these four highlighted players – Robertson being the exception – were within the six changes made to the team that started Saturday’s 2-0 home win over Watford, feels another significant factor to consider.
Rotation
A word that was always likely to be significant for this one – and that will most probably continue to play a sizeable role over the coming weeks, especially if the Reds progress in the Champions League and the FA Cup.
Starting from this Sunday’s visit to the Etihad Stadium, there could be as many as 14 games, across three competitions, in 49 days, for Klopp’s team before the end of the campaign.
Rotation was, indeed, evident both prior to kick-off in Lisbon and within the match.
With a fully fit squad currently available, Klopp had additional room for manoeuvre, too.
Those six changes from Saturday lunchtime’s Watford success saw Joe Gomez, Joël Matip, Jordan Henderson, Curtis Jones, Roberto Firmino and Jota make way for Alexander-Arnold, Konaté, Keïta, Fabinho, Mané and Díaz.
Each of Henderson, Firmino and Jota were then introduced for Thiago Alcântara, Salah and Mané respectively in a 61st-minute triple change, before Gomez and James Milner came on for Alexander-Arnold and Keïta in the 89th.
The depth – of quality, of variety, of experience and youth – within this squad is increasingly striking.
Something that continues to allow longer-term thinking to be applied on a game-by-game basis.
A strategy that could prove especially valuable prior to – and within – that most enticing of clashes on Sunday.