Real Madrid's Thibaut Courtois made several impressive saves to deny Liverpool, including one from Dominik Szoboszlai in the first half.
Just before halftime, a potential penalty was awarded to Liverpool, but it was overturned by the VAR.
The second half saw a flurry of chances for Liverpool, with Virgil van Dijk and Hugo Ekitike both having opportunities to score.
Courtois continued to make crucial saves, but ultimately, Mac Allister found the breakthrough with a powerful header from a free-kick by Szoboszlai.
This was Mac Allister's third goal in the Champions League proper, with two of those coming against Real Madrid.
Trent Alexander-Arnold was introduced in the 81st minute, but received a negative reception from the crowd.
Courtois made another key save to deny Cody Gakpo, but Liverpool held on to secure a vital win.
This victory marked a significant milestone for Arne Slot's Liverpool, who earned their first back-to-back wins since a seven-match winning streak ended in September.
Real Madrid, on the other hand, have struggled against English clubs, winning just two of their last 10 meetings.










