Jurgen Klopp hailed Unai Emery as a "world-class coach" and vowed Liverpool will not underestimate Champions League semi-final opponents Villarreal.

The Reds are still in contention for an unprecedented quadruple and enter Wednesday's first leg with Villarreal at Anfield as strong favorites to advance to next month's final.

However, the Spanish club stunned Juventus in the last 16 and followed that up by eliminating a much-fancied Bayern Munich side in the quarter-finals.

Villarreal's domestic form has improved of late, meanwhile, having won back-to-back LaLiga games – against Getafe and Valencia – to move into seventh place.

Liverpool have progressed from nine of their previous 11 European Cup and Champions League semi-finals, but Klopp is taking nothing for granted against Emery's Villarreal.

"We are here because we got the results we needed," Klopp said at Tuesday's pre-match news conference.

"It's special to be part of the semi-final. It's a massive game. So many coaches and players work their socks off to be close to a semi-final, so we have to cherish it but enjoy it.

"We face a difficult opponent. They are made for this competition. The way they set up is really good.

"They may have had a little advantage where Juve and Bayern maybe underestimated them. That never happens with us, no chance of that. That advantage may have gone.

"They are a good football team that wants to make history. It would be the first time they would make the final, which is massive for them. But for us, it's the same importance."

Emery guided Sevilla to a 3-1 Europa League final win over Klopp's Liverpool in 2016 – one of 11 trophies he has won across an 18-year coaching career.

He took charge of Villarreal in July 2020 following a disappointing stint at Arsenal and guided the Yellow Submarine to Europa League glory last season.

"I have a lot of respect for Unai and Villarreal," Klopp added. "I've analyzed them properly, and wow. Impressive.

"Unai is a detailed-obsessed manager who prepared for all different situations in a game. That's what his team executes. Different ways to press and react to different results.

"It's really, really impressive. Unai is a world-class coach and doing an incredible job there. The good thing about the analysis is we're not involved in those games.

"We must make life as difficult for them as possible. That's what we try to do over these two legs."

Liverpool beat Villarreal 3-1 on aggregate in their only previous European encounter, in the 2015-16 Europa League semi-final, with both teams winning their home leg.

Villarreal have not won any of their last eight away games on English soil, a run that includes a 2-1 Champions League group-stage defeat to Manchester United in September.

And Klopp will be looking to take a victory to Estadio de la Ceramica for next week's reverse fixture as Liverpool aim to make it a clean sweep of trophies this season.

"We have two halves to play. We know when we to go Villarreal, it will be an emotional atmosphere," Klopp said. "There are moments where we will suffer tomorrow.

"I know that already and that's what we have to be ready for. There's no need to be nervous, that's how it is. This advantage at home we have to use.

"Whichever result we will get, we will fight with it. It means everything to us to reach the Champions League final."