Goals from Darwin Nunez and Mohamed Salah saw the Reds capitalise on a whirlwind start by going two up inside the first 14 minutes but Real emerged without sustaining further damage and were back on level terms at half-time thanks to Vinicius Jr’s double.
Eder Militao headed the visitors in front early in the second period, before a Karim Benzema brace earned the holders a commanding advantage prior to the second leg at the Santiago Bernabeu.
Team news
Nunez was deemed fit to start as Jürgen Klopp selected an unchanged line-up following Saturday’s win at Newcastle United.
At the age of 18 years and 122 days, Stefan Bajcetic became the youngest player to start a Champions League game for Liverpool.
Liverpool: Alisson, Alexander-Arnold, Gomez (Matip, 73), Van Dijk, Robertson, Fabinho, Bajcetic (Elliott, 85), Henderson (Milner, 73), Salah, Nunez (Jota, 64), Gakpo (Firmino, 64).
Unused subs: Adrian, Kelleher, Keita, Oxlade-Chamberlain, Jones, Tsimikas, Carvalho.
First half
Feeding off the energy transmitting from the stands, Liverpool surged into an early two-goal lead, with Nunez’s opener clocked at three minutes and 10 seconds – the club’s fastest Champions League goal on home turf.
Sublime goal it was too, as the Uruguayan made a darting out-to-in run and connected with Salah’s incisive pass with a deft flick of his heel.
Salah then body-swerved his way through Eduardo Camavinga and David Alaba before rolling a shot wide but the Egyptian had his goal moments later.
Thibaut Courtois’ touch let him down after he had received a back-pass and Salah nudged home the loose ball to overtake Steven Gerrard and become the Reds’ all-time leading scorer in Europe.
Inevitably, Real grew into the contest once the early frenzy had dissipated and Vinicius hauled them back into the game by whipping an unstoppable hit into the bottom corner.
A goal-saving, last-ditch block by Dani Carvajal denied Nunez as Liverpool sought to restore their two-goal cushion but the visitors’ attacking threat was rising and they levelled nine minutes before the break when Vinicius blocked Alisson Becker’s attempted pass and the ball looped into the empty net.
Second half
With the match delicately poised, the next goal felt crucial in determining the outcome and, just two minutes after the restart, Real got it when Militao headed home Luka Modric’s free-kick.
It was 4-2 soon after when Benzema’s shot took a heavy deflection off Joe Gomez and duly wrong-footed Alisson.
Klopp introduced Roberto Firmino and Diogo Jota from the bench, the duo replacing Nunez and Cody Gakpo, but the Reds were struck on the counter-attack midway through the half.
Again it was Benzema who applied the finishing touch and Liverpool now face a three-goal deficit in Spain next month.
Attendance: 52,337