An early strike from Saul Niguez gave Atletico Madrid a 1-0 win over holders Liverpool in Tuesday's Champions League last-16 first leg at Wanda Metropolitano.
Atletico had won just one of their last seven matches ahead of this tie, but they took the game to Liverpool from the off and opened the scoring through Saul's fourth-minute strike.
Returning to the scene of their magical sixth European Cup triumph in June, the visitors dominated possession but failed to register a single attempt on target in response.
Just a third defeat in all competitions this season leaves Jurgen Klopp's men with it all to do in the return fixture at Anfield on March 11.
Koke's set-piece delivery bounced off Fabinho and squirmed through for Saul, who stabbed the ball past Alisson from point-blank range to give Atletico an early lead.
Atleti pushed for a second goal and an error from Virgil van Dijk gifted Alvaro Morata a free shot from a tight angle, but Alisson was equal to the low attempt.
Liverpool took time to grow into the contest and had the ball in the net through Mohamed Salah after 26 minutes, only for Roberto Firmino to be flagged for offside in the build-up.
Salah flashed a header wide from Liverpool's next big chance eight minutes into the second half as the hosts continued to withstand the pressure.
Jordan Henderson guided a first-time effort just wide before limping off injured in the final 10 minutes as the reigning champions were left frustrated on their return to Madrid.
What does it mean? Advantage Atletico at Anfield
Atletico eliminated Liverpool in their only previous knockout tie - a 2009-10 Europa League semi-final - and they are in a great position to do likewise in next month's return leg.
Diego Simeone's men are known for their ability to frustrate opponents and a draw of any sort at Anfield will send them through.
Super Saul strikes again
Saul was in the right place at the right time to fire Atletico ahead - just the second goal Alisson has conceded in 2020.
Only Antoine Griezmann (six) has scored more goals in the Champions League knockout phase for Atleti than the Spain international (five).
Odd Mane out at Metropolitano
Sadio Mane was Liverpool's match-winner against Norwich City at the weekend but could not find a way through Atletico's packed defence.
He was involved in a running spat with Sime Vrsaljko and was close to being shown a second yellow card before half-time, perhaps explaining his departure at the interval.
Key Opta Facts
- 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 Red Star Belgrade).
- Atletico remain unbeaten in 13 home games in the Champions League knockout stages under Diego Simeone (W9 D4), keeping 11 clean sheets across those matches.
- 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).
- Two of Liverpool's three defeats in all competitions this season have come in the Champions League, also losing 2-0 at Napoli in September 2019 (the third defeat being their 5-0 loss to Aston Villa in the EFL Cup in December 2019).
- Since the start of the 2013-14 season, Atletico's Jan Oblak has kept 26 clean sheets in 49 Champions League games; no other goalkeeper has more in the competition in this time (level with Marc-André ter Stegen, 26 in 57 games).
- Liverpool failed to attempt a single shot on target for only the second time in their 251 games under Jürgen Klopp in all competitions (also v Napoli in October 2018 in the Champions League).
Atletico host Villarreal on their return to LaLiga action on Sunday, while Liverpool welcome West Ham to Anfield in the Premier League in six days' time.