Liverpool were left with an uphill task to salvage their hopes of European glory after suffering their worst half of Champions League football in 16 years at the hands of Real Madrid.
The Reds conceded to Vinicius Junior and Marco Asensio in the opening 45 minutes to fall 2-0 behind.
Such was Jurgen Klopp's concern that the manager was moved to make an unusually early substitution in a bid to turn the tables on Tuesday's first-leg clash.
Reds caught cold in Madrid
Klopp's men were comprehensively outplayed in the first half in the Estadio Alfredo Di Stefano, failing to muster even a single shot against the accomplished Madrid.
The hosts, meanwhile, took their two best chances to open a commanding lead.
Vinicius streaked clear after 27 minutes after receiving Toni Kroos' brilliant lofted pass and finished with ease past Alisson, and the goalkeeper was caught out once again by Asensio less than 10 minutes later, largely thanks to a horrendous error from Trent Alexander-Arnold who headed the ball directly into the forward's path on the edge of his own area.
Not since 2005's Champions League final against Milan have Liverpool conceded twice before the break in a single game in the competition, while more than seven years have passed since they have failed to record an attempt on goal in a a first half.
Klopp did not wait to make changes, sending on Thiago Alcantara for Naby Keita after just 41 minutes. Keita was making only his second start in the competition this season, with the previous coming against FC Midtjylland when Liverpool had already qualified from their group, and he endured a nightmare evening in the Spanish capital.
Europe's comeback kings
While the situation looks bleak for the Reds, it is also one they have recovered from in the past.
During the aforementioned final against Milan, for example, they went three goals behind before pulling the game back to 3-3 and eventually prevailing on penalties to lift their first European Cup or Champions League title since 1984.
Two years ago Klopp's men were also staring elimination in the face after suffering a 3-0 thrashing at the hands of Barcelona in the semi-final first leg at Camp Nou, but on that occasion the Reds were also able to recover, downing Lionel Messi and co 4-0 in the return match to progress to the final, which they also won at the expense of Tottenham.
They will have to pull off a similarly impressive comeback to reach the semis this time round, despite Mohamed Salah's early strike after the break, as Vinicius struck again to give Madrid a 3-1 win on the night which leaves them well-placed for the return leg at Anfield.