LISBON — It just had to be Luis Diaz.

The Colombia winger was the last player Benfica supporters inside the atmospheric Estádio da Luz wanted to see race onto a through-ball and produce an emphatic finish to complete a 3-1 win for Liverpool in the first leg of the Champions League quarterfinals on Tuesday.

After all, Diaz was playing for Porto, Benfica’s big rival in Portugal, until he was signed by Liverpool in January. No wonder he was whistled by home fans — and even targeted with objects thrown from the stands — as he wheeled away in celebration following his crucial third goal in the 87th minute.

It was a brilliantly taken goal, too, as Diaz latched onto Naby Keita’s deflected pass that split Benfica’s defense before rounding the goalkeeper and slotting his finish into the unguarded net from a tight angle.

“He got a nice reception, didn’t he?” Liverpool defender Andrew Robertson said, smiling. “It was a good finish for him and a really important goal for us. It gives us a two-goal cushion, which makes a difference.”

Diaz, who was jeered whenever he touched the ball, played a big part in Liverpool’s second goal, too, when he nodded down a pinpoint long pass by Trent Alexander-Arnold to allow Sadio Mane to tap home from close range in the 34th. That built on Liverpool’s opener scored by Ibrahima Konaté — the center back’s first for the club — off an outswinging corner from Robertson in the 17th minute.

Benfica, playing in the quarterfinals for the first time since 2016 after eliminating Ajax in the last 16, could easily have been further behind by halftime as Liverpool pressed high and was much sharper with its passing. But the hosts took the game more to the six-time European champions in the second half and Uruguay striker Darwin Núñez capitalized on a mistake by Konaté to pull a goal back in the 49th.

Konaté blotted what was otherwise a strong defensive display by failing to clear Rafa Silva’s cross from the right. The ball went through his legs and landed at the feet of Núñez, who took a couple of touches and delivered a composed, sidefooted finish beyond the sprawling Konaté and into the bottom corner.

There were a few more rocky moments for Liverpool — in one of them, goalkeeper Alisson Becker was almost dispossessed on the edge of his area by Silva — before Diaz’s strike ensured Jurgen Klopp’s team would clinch a fifth straight win in all competitions.

“Coming here and winning an away game in the Champions League is tough,” Klopp said. “Benfica fought for their lives. We gave them a little bit too much but they deserved the goal as well.”

Still, the Reds passed the latest test in their bid for an unprecedented quadruple of trophies, with the semifinals now in sight. They have already won the English League Cup, are in the semifinals of the FA Cup, and are one point behind leader Manchester City in the Premier League.

Klopp even took the option of bringing off star attackers Mane and Mohamed Salah in the 61st minute, perhaps with the league showdown against City on Sunday in mind.

City also will go into that game on the back of a win in Tuesday’s other quarterfinal, 1-0 over Atletico Madrid.