Jurgen Klopp has warned his Liverpool players that their Champions League round-of-16 clash against Atletico Madrid will be "one of the most difficult things in the life of a footballer" after admitting that Diego Simeone's team can end his unbeaten record in European knockout ties at the club.
Liverpool have not lost a two-legged tie in Europe since Brendan Rodgers' team suffered a penalty shootout defeat against Besiktas in the Europa League round of 32 in February 2015.
Since that loss, Liverpool have overcome the likes of Barcelona, Bayern Munich, Manchester City and Roma in the knockout stages of the Champions League and reached three European finals -- one Europa League and two Champions League -- under Klopp.
But with Liverpool returning to the Estadio Metropolitano, the scene of their Champions League final win against Tottenham last June, Klopp believes that Atletico pose serious threat to the Anfield club's long unbeaten record.
"Playing Atletico is one of the most difficult things in the life of a football player," Klopp said. "They are a really well-organised football machine, squeezing results.
"If there is a team against who you have to be at your best in all departments, it is Atletico because they give you absolutely no presents.
"If you don't play your very best, you have no chance.
"It looks like a real, proper machine. If something happens, they are there. They close you down with two or three players, turn you around and counter-attack.
"They are in a transition period, that's normal, but you do not get a lot of chances against them, so it's really difficult.
"They have not played as badly as people have said they have this season, so the team that gets through will be the one that plays the best in the two games. But we are here, we are really ambitious and we will give it a try.
"Maybe Atletico haven't played against a team like us, so we shouldn't forget that. Our readiness to fight is exceptional."
Despite highlighting the threat posed by Atletico, who have twice reached the Champions League final under Simeone, Klopp insists that Liverpool are a contender to win the European Cup again this season.
And he has cited the team's recent record in Europe as a reason for his confidence.
"It's impressive, that record," he said. "Every time I have been involved in a European competition with Liverpool, we have ended up in the final, which is nice, although not when you don't win.
"We want to be one of the teams who can get there. As a team, we have the chance to get there.
"We struggled a bit in the group stage and came through, but we are quite convincing in the knockout and hopefully it will be like this as well.
"We don't feel like the winners of last season. We feel like one of the contenders for this year and we want to go to Istanbul for the final."
Asked to assess the Premier League leaders, Simeone was cognizant of the challenge his side will face on Tuesday.
"We face a great team, well-coached by a good, different coach, with alternatives in how the team play, counter-attacking, positional play, a strong aerial threat, and they've been building every year that he's been at the club," said Simeone.
"Even when the departure of Coutinho seemed like it could trigger the team breaking up, instead the opposite happened and they got stronger, and that speaks well of the club, the coach and the players."
Simeone added that he sees similarities between his and Klopp's approach as coaches.
"Yes, maybe in details, above all the intensity, I remember his Dortmund, a similar team to what he has now, in that trait of intensity and competitiveness, we're similar," he said. "The teams show our characteristics as coaches. Then the potential of the players means the teams play in different ways.
"I have no doubt that, talking about great teams over time, this Liverpool will go down in history because it has different facets to all those others we've admired. I like this team more because it's more direct, more intense. I admire them."