The two Premier League heavyweights are now almost at full-strength following injuries and transfer speculation surrounding a number of their key players.
But who would make a combined XI between the players available? Goal uses their form so far this season to put together the best possible team...
SIMON MIGNOLET (Liverpool): With questions starting to be asked regarding Petr Cech's consistency, Mignolet's form towards the end of last season and start to the current campaign sees him take the goalkeeping position. The Belgium international's penalty save against Hoffenheim was key in the Reds's passage into the group stages of the Champions League.
SHKODRAN MUSTAFI (Arsenal): Despite his return to the starting XI coinciding with the defeat to Stoke City, the Germany international has been a figure of consistency for the Gunners since his arrival 12 months ago, and their reluctance to sell to Inter is testament to that.
JOEL MATIP (Liverpool): While there are clear deficiencies within the Liverpool defence, the former Schalke centre-back is by far their most reliable performer, particularly with Dejan Lovren continuing to struggle.
NACHO MONREAL (Arsenal): Though not a natural centre-back, the 31-year-old has been gradually improving since Arsene Wenger's switch to a back three and has gone some way to securing a place in Spain's World Cup squad.
TRENT ALEXANDER-ARNOLD (Liverpool): With Nathaniel Clyne nursing his way back to full fitness, teenager Alexander-Arnold has taken his opportunity to establish himself in the Liverpool first-team. His superb free-kick against Hoffenheim illustrated his attacking threat and though he still has work to do defensively, he edges out the more experienced Hector Bellerin in this XI.
AARON RAMSEY (Arsenal): Opened his account for the season against Leicester City and seems to be far more comfortable in a midfield two rather than a three. Edges out team-mate Granit Xhaka, who despite some eye-catching passes has twice already given the ball away leading to goals being conceded.
EMRE CAN (Liverpool): After being called upon to cover for Jordan Henderson for much of last season, the Germany international finally seems to be finding his feet in the Premier League. Having always been a fine passer of the ball, he now seems to have found his goalscoring boots, as underlined by his double against Hoffenheim on Wednesday.
SEAD KOLASINAC (Arsenal): Already being dubbed one of the signings of the summer, the free transfer from Schalke has added some much needed physicality to the Gunners line-up, while he also netted the winning goal in the Community Shield.
SADIO MANE (Liverpool): With Philippe Countiho still on the sidelines amid speculation regarding his future, the Senegal international has further pressed his claim to be Liverpool's most important player having scored in both Premier League matches thus far.
MOHAMED SALAH (Liverpool): Much was expected of the former Chelsea winger following his big-money arrival from Roma in the off-season and he has hit the ground running with two key goals already. Indeed, he seems to have struck up a superb understanding with Mane and Roberto Firmino.
ROBERTO FIRMINO (Liverpool): Before Wednesday, Alexandre Lacazette may have taken this position in the combined XI, but after Firmino put his former side, Hoffenheim, to the sword at Anfield it would be wrong not to include him given the side is selected based on recent form.
Have we got it right? Is there someone missing from our XI that deserves a place? Have you say in the comments below!