The winners will take on either Sevilla or Shakhtar Donetsk in the final at St Jakob-Park on 18 May.
- The match kicked off at 8.05pm
- What Liverpool need to do - FULL PERMUTATIONS
- Villarreal are currently fourth in La Liga
- Liverpool are eighth in the Premier League
- Reds dramatically beat Borussia Dortmund in the last round
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Liverpool manager Klopp insists Villarreal's wild celebrations in their first-leg victory provides no motivation for his side.
The Spanish club arrive at Anfield for the Europa League semi-final with a 1-0 lead from the first leg courtesy of a last-minute winner, which sparked jubilation among the home squad and fans.
Klopp played down the significance of that goal a week ago and he will not use it to gee up his players ahead of a pivotal night.
"They scored a goal in the last minute, so if they hadn't celebrated something would have been really wrong," he said.
"The only thing I thought in this moment was 'Half-time'. Nothing happened. They have to come to Anfield.
"I am still feeling this so the feeling is we are halfway through and I know how difficult it is.
"I sense the chance more than I am afraid of something - so let's try."
Klopp is an emotional character on the touchline but he will keep things in check and expects his players to do the same.
"I am fine (emotionally) - even when it doesn't look like it," he added.
"We know we have 90-something minutes. It's not about being patient in a patient way, it's about being patient with a clear direction.
"We need to show in each situation that we know about the game and the importance, not with pressure but with joy."
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