LIVERPOOL, England — Liverpool looks like being one European giant too many for Villarreal.

Wins in the Champions League semifinals are rarely as routine as Liverpool’s 2-0 first-leg victory on Wednesday over the Spanish underdog, which appears to have finally come unstuck on a fairytale run that has already accounted for European football royalty in Juventus and Bayern Munich.

Liverpool, still on course for an unprecedented quadruple of major trophies, proved to be a bigger test. The six-time European champions slowly dismantled the limited challenge of Villarreal on another night when they were swept along by the power of Anfield.

The goals came early in the second half — and within 133 seconds of each other — as Villarreal left back Pervis Estupinan unwittingly deflected a cross by Jordan Henderson into his own net in the 53rd minute, with goalkeeper Geronimo Rulli only managing to tip a looping ball into his own net.

One goal can quickly turn into two in these energy-charged European nights at Anfield and that’s what transpired again, with Villarreal still shaken up from conceding the opener when Sadio Mane ran onto Mohamed Salah’s through-ball and toe-poked a low finish beyond Rulli.

The second leg takes place at Estadio de la Cerámica on Tuesday and only a major surprise will prevent Villarreal — a team only in seventh place in the Spanish league and filled with players who failed to make it in England — from bowing out, just like in 2006 in its only other appearance in the semifinals.

Liverpool manager Jurgen Klopp struck a cautious note despite the one-sided nature of the first leg.

“Nothing has happened yet,” he said. “We’re playing a game and it’s 2-0 at halftime. You have to be completely on alert, 100% in the right mood.”

Klopp has built a formidable winning machine that looks even more complete than the team which won the Champions League in 2019, a year after also reaching the final and losing to Real Madrid under the German coach.

As his players did a lap of honor inside Anfield after the final whistle, Klopp waved to the crowd and tapped the club crest on the front of his thick coat.

Another win. Likely another Champions League final. And, amazingly, the quadruple is still on for a team that has already won the English League Cup, is into the FA Cup final and is only a point behind Manchester City in the Premier League title race.

It could yet be a Champions League final between the two northwest rivals, with City taking a 4-3 lead over Real Madrid into the second leg of their semifinal in Spain next Wednesday.

A sea of yellow-clad Villarreal fans — at around 5,000, they amounted to almost 10% of the population of the town in eastern Spain — swarmed its way from Liverpool city center to Anfield ahead of the game. A rendition of The Beatles’ “Yellow Submarine,” which is the nickname of visitors, was well-received by the lively away contingent before kickoff.

That was as warm as the welcome got.

Liverpool snapped into tackles and pressed high from the first whistle, meaning Villarreal’s players hardly got out of their half all match.

“The reality is, they are in the best moment,” Villarreal coach Unai Emery said of Liverpool. “They are in the favorite to win this competition.”

Yet, with Emery setting up his team with his back four screened by a deep-lying and narrow midfield four, Liverpool was initially starved of space in what quickly became tantamount to an attack vs. defense exercise.

There were plenty of half-chances — Mane headed wide off his face, Salah curled over then volleyed over, and Thiago Alcantara smashed a long-range shot off the outside of the post — but Villarreal held out until halftime.

Then it all went wrong.

The two goals came in between two disallowed efforts, by Fabinho then Andrew Robertson, and it was only Liverpool’s players taking their foot off the gas that stopped an even bigger victory.

“We had put in a perfect performance up to the first goal,” said Rulli, who called Liverpool the best team in the world. “After that, we were a bit uncertain.”

Klopp used the opportunity to take a number of key players off early, with a potentially tough Premier League game against Newcastle on Saturday sandwiched between the six-day turnaround for the Villarreal games.

Liverpool’s quadruple charge is likely to be heading deep into May.