Former Villarreal star Robert Pires believes Liverpool are "the best team in Europe", but insists the Yellow Submarine can overturn a 2-0 first-leg deficit to reach the Champions League final.
After a routine Liverpool win at Anfield last Wednesday, Villarreal will attempt to become just the second team to overturn a two-goal first-leg deficit in a Champions League semi-final (after Liverpool's 4-3 aggregate win over Barcelona in 2019).
Villarreal did not manage a single shot on target in their away reverse, but Pires' former club did win their only previous home game against Liverpool in European competition (a 1-0 win in 2015-16's Europa League semi-finals).
Although Pires said quadruple-chasing Liverpool are the best team on the continent, he does not think the result is a foregone conclusion on Tuesday.
"Of course Villarreal can go through," he said in comments reported by AS. "We know how complicated it is, we cannot deny that. We know the level of Liverpool and their quality, they are very good and very strong, but Villarreal has not said the last word.
"For me, Liverpool is the best in Europe at the moment and that makes it a great challenge. For this reason, Villarreal, which is a very solid team, suffered a lot in the first leg. But they came out alive, and knowing Emery and the quality of this team, I wouldn't be comfortable.
"To that they must add a bit of luck, we know that these comebacks must have that point of fortune to turn the tie around. I tell people that if the player feels that the fans are with you and push, anything is possible.
"Hopefully Villarreal will reach the final in Paris. That is my wish, I would very much like it to be."
Villarreal have never lost a home match in the Champions League knockout stages, although they have drawn five of their seven such fixtures.
Before Pires joined the Yellow Submarine, for whom he made 131 total appearances across four seasons, he lined up as an opposition player for the club's only previous Champions League semi-final appearance, with Arsenal.
The Gunners reached the final with a 1-0 aggregate win after clinging onto a goalless draw in Spain, with Jens Lehmann saving Juan Roman Riquelme's late penalty, and Pires said his memories of that contest make him believe Villarreal will provide Liverpool with a stern test.
"This team is not eliminated, far from it," he added. "I played the other semi-final with Arsenal and we also had an advantage, so we hoped to get through without suffering. And the reality was very different.
"We suffered like dogs in that game. We came from eliminating Juventus and Madrid, we were very confident and secure, but we arrived here and had a really bad time. I don't know what happened to us, but it was the game in which we suffered the most of all.
"That's why I think Villarreal can give Liverpool a cane. I know, I've lived it."
Villarreal are unbeaten in 12 home matches in all competitions, winning eight, and recorded an incredible 1-0 success against Bayern Munich in their last home Champions League outing.