The Reds suffered injury-time heartache in the first leg at El Madrigal last week, as Adrian pounced to give Marcelino’s men a slender advantage at the end of a tightly contested match.
Klopp made eight changes to his XI for Sunday’s Premier League trip to Swansea City and the likes of Daniel Sturridge and Martin Skrtel did little to advance their claims on a starting place for Thursday’s pivotal showdown as Liverpool slumped to a 3-1 defeat.
“We have to accept the result because our performance wasn’t good enough,” Klopp told the club’s official website.
“I’m especially a little bit disappointed because if we had played our normal game for 90 minutes we could have won the game, but we didn’t play a normal game and that was the problem.
“We got it back to 2-1 but then we conceded again and the goals were too simple, too easy for Swansea. I’m not looking for an excuse and I think we could have played better but we didn’t.
“We played like we played and I saw it for the whole 90 minutes and there was not a lot I enjoyed, to be honest. We have to think about it and we have to recover, which is very important, and we will play much, much better than we did on Sunday.
“We have to accept the result, which is what we do, and then we work and we will be better on Thursday.”
Christian Benteke enjoyed a rare high-point in his lacklustre debut season with Liverpool by getting on the scoresheet at the Liberty Stadium, but Klopp could again decide to operate without a conventional centre-forward and play Roberto Firmino as his most advanced attacker.
By contrast, Villarreal were comfortable 2-0 winners at Valencia in La Liga on Sunday – Adrian finding the target as one of 10 alterations to the line-up – although Marcelino was without Eric Bailly due to a groin injury sustained during the first leg and will hope the influential centre-back recovers in time.
“Throughout the season, we have used rotations,” Marcelino explained. “We all trust and work with the same idea of play and we are all participants in that.
“We have shown respect, work, attitude and sacrifice.
Striker Leo Baptistao is back in training following a muscular problem and has been named in the Villarreal squad, alongside Bailly.
Klopp has a lengthy absentee list to cope with – Mamadou Sakho has been suspended by UEFA after failing a blood test, while long-term knee injury victims Jordan Henderson, Joe Gomez and Danny Ings have been joined on the sidelines by Divock Origi and Emre Can (both ankle).
Key Opta stats
– Sides holding a 1-0 home advantage after the first leg of Europa League knockout ties have progressed 59 per cent of the time since the 2009-10 season (16 out of 27).
– Liverpool have succeeded in three of their previous five semi-finals in European competitions after losing the first leg away from home.
– The Anfield club have won their past seven home second-leg ties, conceding only once in the process.
– Villarreal have only failed to score once in their last 32 Europa League matches, while Liverpool have left four of their past five encounters with Spanish sides scoreless.
– Only Athletic Bilbao’s Aritz Aduriz (10) has more Europa League goals this season than the nine provided by Villarreal’s Cedric Bakambu.
- 59% of teams to win 1-0 at home in the first leg of Europa League knockout ties have gone on to progress to the next round (since 2009/10, 16 of 27).
- The Reds have progressed from three of their previous five semi-finals in European competition after losing the first leg away from home.
- The Reds have won their last seven home second leg ties in European semi-finals; conceding just one goal in that time.