I wonder why you think that Arsenal can get a very simple win from Liverpool, it is laughable indeed for you to think so. Even if Liverpool is not as strong as they used to be doesn't mean that any team will beat them as if they are Wolves or Watford and go their ways.
Have you watched Arsenal play this season? They're playing just like Manchester city and that's not a surprise considering their manager was a former assistant to Pep under Manchester city. Arsenal are on the front foot attacking from the beginning of the game until the very last minute. The only problem they're having at the moment is been defensively strong when they get counter attack due to the high defensive line they're keeping.
This is the flaw Manchester united were able to exploit and won the game with just counter attacking.
Liverpool aren't the same Liverpool of last 3/4 season that we knew, they're totally different this season and their players are off form. If Liverpool was to win Arsenal in anyway then they have to play just as Manchester united did. Allow Arsenal to have possession of the ball then destroy them with counter attacking but no, Liverpool would wan to go head to head with arsenal and that's where they'll lose the game.
Against Manchester United right ? Thomas Partey was absent due to injuries and with the introduction of Sambi Lokonga in that game, he couldn't handle the heat and pressure from Manchester United midfielder's. Thomas Partey is much more of an experienced defensive midfielder to Lokonga honestly. Ball recovery and tracking those in between passes was not done much by Sambi. Thomas Partey's service would have done Manchester United harm but good Jesus! Thanks Goodness he was absent.
Also what they lacked was game management, if you watched Barcelona yesterday, the likes of Busquet and Pedri that's what they do best to manage the game from the start to end, they both determine how the game went. Arsenal players lacked that and Manchester United managed better than them with Bruno Fernandez and Christian Erikson.
Much favorite for the weekend against Liverpool, I hope they pump Liverpool, they have had a good start consistency is all that matters now, they drop points drastically during December/January but if they can keep up with those points then they can win the League. But would Pep Guardiola let em ? Gradually turning the league into a farmers League..