Dani Ceballos has revealed he was stunned by how good Liverpool were during Arsenal's 3-1 loss to the Champions League holders in late August.
The Gunners have been tipped by many to finally break back into the Premier League's top four this season after a few years away from Europe's elite club competition, but were given a quick reminder of the gap in quality between the likes of Liverpool and Manchester City and those scrapping for European qualification during a chastening loss on Merseyside.
While Arsenal did claw one back through Lucas Torreira in the 85th minute, Ceballos admitted the team he faced last month is one of the best he has ever seen.
"I had never seen anything like it," he told the Daily Mail. "I've not seen up until now a team that plays better, that presses better. That game had quite an impact on me.
"They suck the air out of you. You spend so much time defending and when you want to catch your breath and get on the ball for a bit, they've taken it from you again.
"I think Jurgen [Klopp] now has the team he first had in mind when he started four years ago."
However, the Real Madrid loanee was also quick to argue Gunners manager Unai Emery could achieve what Jurgen Klopp has at Anfield at the Emirates, pointing to his debut season in north London last term as evidence.
He added: "The difference is that when Unai comes into Arsenal they had been on a less positive run for three or four years.
"His arrival has been really positive for the club and will be positive in the long term. In a few years Arsenal can be one of the top ten sides in the world able to compete for everything."
Arsenal are next in action on Sunday, when they face Watford at Vicarage Road.