Liverpool must come from behind in their Champions League last-16 tie against Atletico Madrid after a 1-0 first-leg defeat in the Spanish capital on Tuesday, only their third defeat of the season.
Struggling domestically but always dangerous in Europe, Atletico got an early winner as Saul Niguez poked home from close range as the ball fell kindly to him from a corner in the fourth minute.
Liverpool dominated the ball but could not break through the stubborn Atletico defensive wall, with Mohamed Salah going close twice, and Jordan Henderson steering just wide in the second half.
The European champions ended the game with no shots on target, and have a task on their hands in the second leg at Anfield in three weeks, at 8pm on March 11.
Atletico Madrid: Oblak (6), Vrsaljko (7), Savic (7), Felipe (7), Lodi (8), Koke, Saul (7), Thomas (8), Lemar (7), Correa (7), Morata (7)
Subs: Llorente (6), Vitolo (6), Costa (6)
Liverpool: Alisson (6), Alexander-Arnold (5), Gomez (6), Van Dijk (6), Robertson (6), Fabinho (5), Henderson (6), Wijnaldum (6), Mane (5), Salah (5), Firmino (6)
Subs: Origi (4), Oxlade-Chamberlain (5), Milner (N/A)
Man of the match: Thomas Partey
How Atletico frustrated the champions
Returning to the scene of their Champions League win in June, where half of the Wanda Metropolitano was behind them, Liverpool this time struggled early on in a Madrid caldron.
An early Koke corner evaded everyone in the box before hitting the foot of Fabinho, then fortuitously falling to Saul to turn home from close range for the opener.
Liverpool reacted well and had all of the ball - 75 per cent in the first half, and in dangerous areas - but struggled to break down the Atletico defence. In a rare break, Alvaro Morata nearly capitalised on an equally rare Virgil van Dijk mishap, but saw his shot from an acute angle blocked by Alisson.
Liverpool had the ball in the net not long after as Jan Oblak's miscued clearance fell to Salah 40 yards out; he instinctively passed forward to Roberto Firmino, using him as a wall before Salah rolled the ball into the net, only for the flag to go up for an offside against the Brazilian.
The visitors' best chance then fell to Salah after good work from Sadio Mane and then Firmino, but the Egyptian's goal-bound effort from 12 yards was superbly deflected clear by Felipe.
Jurgen Klopp made a change at half-time as Mane made way for Divock Origi, but it was more of the same as Salah headed wide unmarked from a Joe Gomez cross.
Jurgen Klopp made two changes following Saturday's win at Norwich as Sadio Mane and Fabinho returned to the starting line-up in place of Alex Oxlade-Chamberlain and Naby Keita. For Atletico, Diego Costa was on the bench, with Alvaro Morata starting.
Atletico arguably had the best chance to score the second goal as Morata met a Renan Lodi's centre in acres of space, only to slip as he went to shoot from 10 yards.
Henderson came within inches of an equaliser, steering a side-footed effort from 12 yards just wide, and there was concern late on as the Liverpool captain was then forced off with a hamstring injury.
Diego Simeone was the conductor for the home fans' vocal support, overly animated on the touchline even by his standards, and it eventually saw them through without any damage on their own goal.
For Liverpool and Klopp, the feeling of defeat may be a rarity, but their dominance of this game will give them hope going into the second leg on Merseyside.
What the manager said...
Liverpool boss Jurgen Klopp: "I have no problem with the result. I saw a lot of happy faces from Atletico, I get that because it was a big win, but it is not over yet. The atmosphere was difficult for the referee to deal with. After 30 minutes three Atletico players were already on the ground and not injured, the referee just needed to feel the game a little more.
"It was clear the crowd wanted to help tonight in a different way to how our crowd helps us, and that made it a very emotional game. We had to try and be really calm in making decisions, and I like a lot of parts of our game, but of course we have to be better in the final third and we will try it."
- Since the start of last season, Liverpool have lost six of their 10 away games in the Champions League (W4); no side has lost more away from home in the competition in this time (level with Crvena Zvezda).
- Atletico Madrid remain unbeaten in 13 home games in the Champions League knockout stages under Diego Simeone (W9 D4), keeping 11 clean sheets across those matches.
- Liverpool manager Jürgen Klopp has failed to win all seven of his away games against Spanish clubs in the Champions League (D3 L4), including three with Liverpool (D1 L2).
Sky Sports' Adam Bate...
'This is one of the most difficult fixtures in the life of a football player," said Jurgen Klopp before Liverpool's Champions League tie against Atletico Madrid. So it proved as the runaway Premier League leaders, on a run of 43 games unbeaten in domestic competition, were beaten 1-0 in the Metropolitano. Liverpool didn't even muster a shot on target.
'They pressed and they probed, they dominated possession and sustained attack after attack. But while Mohamed Salah headed wide and Jordan Henderson guided a volley just the other side of the same post, the equaliser never came. Liverpool will fancy their chances back at Anfield but this was a reminder that there are still teams capable of thwarting them.'
Liverpool now host West Ham on Monday Night Football, live on Sky Sports Premier League, while Atletico host Villarreal on Sunday evening at 8pm in La Liga. The second leg of this fixture at Anfield is on March 11 at 8pm.