In Jamie Carragher's playing days, his worst-ever opponent was Arsene Wenger's Invincibles.
"This team is the best team I ever played against, and the one team where I would say going into games affected me psychologically," Carragher said on Sky Sports.
"I felt uncomfortable, I didn’t feel good enough, I didn’t feel physically strong, it made me feel smaller and weaker. Against United, you knew they were better than us or Chelsea had the edge on us but you still felt we’d give them a good game. We’ll take them as far as they can."
Addressing another Sky pundit, ex-Gunner Freddie Ljungberg, Carragher continued: "This, Freddie, and your team is what it did to me psychologically.
"I actually think playing this Arsenal team as a right-back, I’m not sure there was any more difficult positions to play in the world, certainly at that time.
"I played right back in that Liverpool team in the early 2000s and you’d get Pires coming inside, you’d get Thierry Henry spinning out to this side and you’d get Ashley Cole on the overlap. And the reason I’d say this team was the toughest to play against was because things happened so quickly.
"That’s the most difficult thing as a defender, you’ve got no time to react. I was an organiser, telling people where to go and organising the team. When you’re playing against a team who play at this pace there’s no time to speak. You can’t pass on information, things are happening so quickly.
"And I think this area of Pires, Cole, Thierry Henry was devastating. I have nightmares thinking about it."
