Villarreal coach Unai Emery was relieved that his side will go into the second leg of their Champions League semifinal with Liverpool with only a 2-0 deficit after their defensive gameplan backfired at Anfield.

Liverpool had looked frustrated in the first half as Villarreal manned the barricades but the hosts got their reward after the break thanks to an own goal and a Sadio Mane strike.

The Spanish side were under the cosh for the entire game and did not manage a shot on target.

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"I have to admit, it could have been much worse," Emery told Movistar Plus.

"We have tried to attack, to pass, to construct but they did not let us do anything and our last resort was to resist defensively in order to survive for the second match.

"We didn't do enough to lament about anything. We have to be humble and try to make the second leg a totally different game. We have to play with more intensity, like we are used to."

Emery's side looked a shadow of the aggressive and daring team that knocked-out Juventus in the last 16 and beat Bayern Munich in the quarterfinals.

However, Liverpool coach Jurgen Klopp called on his side to stay completely alert as they eye a third Champions League final in five seasons, insisting the scoreline could give a false impression.

Klopp, who has won all four of his home Champions League semifinal matches as a manager with Borussia Dortmund and Liverpool -- seeing his teams score 15 times while conceding three -- insisted the job was not done yet.

"It is now halftime [in the tie], no more, no less," Klopp said. "There is still a full job to do, nothing happened yet.

"The best example is you play a game and it's 2-0 at halftime. You have to be completely on alert in the second half and have to be 100% in the right mood.

"They could play the second half like you played the first half, and if they do that then all the advantages we have go away. We go there for the second leg and it'll be a tricky atmosphere, obviously different to tonight. Their players fight for their lives, for their coach."

The Spanish side similarly insisted they are still alive in the tie ahead of next Tuesday's return encounter.

"We are only two goals behind. A lot of things can happen in football and 90 minutes is a long time. If we manage to score early we are back in the tie," centre-back Pau Torres said.

"At home we are a totally different team, we are going to go out there and play to win. We still trust in ourselves, we have no doubt. I can promise our fans they are going to see a Villarreal that they can identify with in the second leg."