Liverpool s Mohamed Salah, centre, is tackled by Atletico Madrid s Rodrigo De Paul during the Champions League group B soccer match between Liverpool and Atletico Madrid in Liverpool, England, Wednesday, Nov. 3, 2021 (AP)
Precision passes from Alexander-Arnold into the heart of the goalmouth set up Diogo Jota and Sadio Mane for simply taken goals in the first 21 minutes.
Atletico looked beaten even before going down to 10 men in the 36th when defender Felipe was shown a straight red card for tripping Mane and his subsequent petulant reaction to the referee.
Liverpool's fourth straight win to open the group stage lifted the 2019 champion seven points clear of second-place Porto with two rounds remaining. Liverpool will be seeded as a group winner in the round of 16 draw on Dec. 13.
The loss for Atletico, which was beaten 3-2 by Liverpool in Madrid two weeks ago, also helped last-place AC Milan, which got its first point in a 1-1 draw at home to Porto.
Atletico hosts Milan, which can still finish runner-up in Group B, in three weeks' time. Liverpool next welcomes Porto to Anfield.
Liverpool is now unbeaten in 16 games this season, and only European champion Chelsea has stopped Liverpool scoring at least two goals. The top two in the Premier League drew 1-1 back in August.
Alexander-Arnold was the expert creator of both first-half goals with the right-back delivering angled balls behind the Atletico back line.
A cross in the 13th bounced for the stooping Jota to guide a header high into the net, then a low and hard pass in the 21st went directly into Mane's path to gently guide the ball past goalkeeper Jan Oblak.
Liverpool threatened to sweep aside Atletico in waves of attacks early in the second half, and Jota had a goal ruled out for offside.
Atletico also had a goal disallowed by a video review, from a deflected shot in the 57th by Luis Suarez, who was jeered by home fans on his return to the club where he played for three seasons until 2014.
Atletico was back at a packed Anfield for the first time since eliminating Liverpool, by winning 3-2 after extra time, in the round of 16 on March 11 last year. That was the day the COVID-19 outbreak was officially declared a pandemic.
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