Jurgen Klopp praised Liverpool's character after they withstood a first-half onslaught from Manchester City to book their place in the semi-finals of the Champions League following Tuesday's 2-1 victory.
After Liverpool won the first leg 3-0 at Anfield, City raised hopes of a comeback when Gabriel Jesus put the hosts ahead inside two minutes of the return fixture at the Etihad Stadium on Tuesday.
Klopp acknowledged his side had to be disciplined in defence – as well riding their luck, with Leroy Sane having a goal ruled out for offside – to only trail by one goal at the break.
However, the visitors weathered the storm and picked off their tiring opponents in the second half, goals from Mohamed Salah and Roberto Firmino clinching victory.
"It was quite difficult tonight, especially with the start with that wonderful goal we served them on a plate," Klopp told BT Sport .
"But, to be 100 per cent honest, I expected something like that to happen. You need to react in the right way. I liked how we reacted immediately after conceding, but then we didn't play enough football in the right way. We were kept under pressure.
"City took all the risks they could take. We needed a bit of luck and some disciplined defending in terms of our formation.
"I was not overly happy at half-time to be honest. We were not compact enough and too many second balls went to City. If we gave them those second balls, they were already in the right place to make three or four passes.
"I knew it would be difficult but we still did it, which is fantastic!"
Pep Guardiola's decision to go all-out attack with his team selection caused Liverpool issues in the first 45 minutes, with the away side at times struggling to get out of their own half.
Klopp admitted his players took time to adapt to City's three-at-the-back system in the early stages – but always believed they would get the chance to do damage on the counter.
"He [Guardiola] took the risk. It was his decision and it could absolutely have been the right one, too," he added.
"In football it's very easy to say that Liverpool won so City got it all wrong, but they could have scored two or three in the first half.
"It was not 100 per cent clear how they would line up at the start with these players – but it was 100 per cent clear that if we got the ball, we would have an opportunity.
"We did not use those opportunities in the first half – we gave the ball away too quickly. It was like every touch we tried to send Salah off to the races, which didn't make too much sense.
"But the Champions League is not about perfection, it's about the result. It's about the character, the mentality and the attitude.
"Again, we created this kind of mood for us, this attitude to fight for the result. I love that. It wasn't our best football game but deserved [to go through] in the end."