Roberto Firmino and Sadio Mane gave the hosts a deserved two-goal lead before the break, and Mohamed Salah added to the advantage in the second half. Daniel Sturridge also got on the scoresheet.
Here's a look at the teamsheet, via James Pearce of the Liverpool Echo:
There were a number of surprises on both sides, but James Benge of the London Evening Standard noted the visitors, in particular, left a lot of expensive talent out of the starting XI:
Liverpool started the match on the right foot and threatened early through Emre Can, while Danny Welbeck also had an early look on goal. It was mostly one-way traffic, however, with a great save from Petr Cech preventing a score from Salah after 11 minutes.
The pressure from the hosts paid off after 17 minutes when Joe Gomez picked out a wide-open Firmino inside the box, and the Brazilian easily headed home the opener. Sportswriter Ryan Bailey anticipated more poor defending:
Jordan Henderson couldn't beat Cech with a smart chip, and the veteran came off his line in time to deny Salah as the Reds didn't let up. The former Roma man produced all kinds of danger and even had a goal called back for offside after 27 minutes.
Mane also went close with a powerful shot and had more luck after 40 minutes, finishing off a beautiful counter-attack. Per Sport Witness, pundit Gary Neville had some harsh words for the Gunners:
Rob Holding missed the final good chance of the half, as he rushed his effort and couldn't trouble Loris Karius.
Francis Coquelin started the second half in place of Aaron Ramsey, with manager Arsene Wenger opting to beef up his midfield.
Karius had a couple of shaky moments early in the second half and nearly handed Welbeck an opportunity on a platter, while Salah and Henderson should have done better after some dodgy defending gave them another look on goal.
Yet another mistake from an Arsenal defender, this time Hector Bellerin, gave the Moroccan a golden opportunity for a third goal, and this time, Salah didn't miss.
Former England international Gary Lineker made a big statement:
The misery continued for the Gunners, as it was Holding's turn to make an error that almost resulted in a fourth goal, with Cech denying Mane at the last second.
Arsenal lost their discipline as the half wore on and tackles started flying in, while the Reds remained focused on attacking and found a fourth goal through Sturridge, who headed home from close range.
Poorly Drawn Arsenal summed up the afternoon from the Gunners' perspective:
The visitors pushed for a late consolation goal, but Olivier Giroud couldn't keep his header on target. Liverpool went closest to scoring in the final minutes, with Cech denying Salah one more time.