Our unbeaten run came to an abrupt end as we suffered a heavy defeat at Anfield.
The game unravelled for us in the second half, after a promising opening half hour or so, in which we played with the confidence we had built after three successive clean sheets.
But once Liverpool took the lead late in the first half, they took control, and despite the best efforts of Aaron Ramsdale, we suffered another chastening away day on Merseyside.
We had a few chances of our own in the first half - Takehiro Tomiyasu's dangerous cross was headed clear, while Alexandre Lacazette's goal was ruled out for offside on Pierre-Emerick Aubameyang.
There was a flashpoint on the touchline late in the first period when Mikel Arteta believed Sadio Mane had led with his arm when challenging Tomiyasu. His anger was clear, and led to referee Michael Oliver showing our manager the yellow card.
With the atmosphere crackling, Liverpool stepped up the pressure - Ramsdale denied Mohamed Salah and then Trent Alexander-Arnold in quick succession, while at the other end Fabinho made a huge sliding block to deny Aubameyang as he led a counter-attack.
But all our hard work was undone five minutes before the break when Mane headed in Alexander-Arnold's free-kick.
It was hugely frustrating, given the work we had put in defensively.
Mane was then booked for a late challenge on Ben White. It was his fourth foul of the game, explaining Arteta's frustration.
The half ended with Sambi Lokonga having a shot from outside the box easily saved by Alisson, as we looked to get back in to the game.
We started the second half in sloppy fashion though. Lokonga gave the ball away twice in dangerous areas, but Liverpool didn't take advantage.
Nuno Tavares however had no such luck when his pass was intercepted by Diego Jota outside the box. The Portuguese forward skipped past his defender, dummied Ramsdale and tucked home to double the lead.
Arsenal were ragged now and beginning to come under more pressure. Ramsdale made a brave save at the feet of Jota and also saved from Salah.
Aubameyang was continuing to work hard up front, and brought a good save from Alisson, with nobody there in a yellow shirt to score the rebound.
Ramsdale again came up with a fine save to deny Jota at point-blank range, as the home forwards grew in confidence.
Salah made it 3-0 with 20 minutes left, finishing a rapid counter attack by converting Mane's fizzed in cross.
Thomas Partey saw his curling effort clawed away by Alisson when it looked to be destined for the top corner, but it was a temporary respite from dealing with the rampant Liverpool forwards.
They competed the scoring late on - Takumi Minamino making it 4-0 with his first touch, scoring at the far post from an Alexander-Arnold cross.
WHAT IT MEANS
The boss made just one change to the side that beat Watford 1-0 prior to the international break. Thomas Partey recovered from injury, and he replaced Ainsley Maitland-Niles in central midfield.
Emile Smith Rowe retained his place on the left, fresh from scoring on his first start for England in the week.
We return to Emirates Stadium next Saturday, for a 12.30pm (UK time) kick-off against Newcastle in the Premier League.
It's our final fixture of November, before the busy December which sees us play eight matches in the month.
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