Jurgen Klopp hailed Manchester City as the "best team in Europe" as Liverpool prepare to host the reigning Premier League champions on Sunday.
Liverpool are the only side still unbeaten in the Premier League after six matches and have not lost in 16 league games as they sit a point clear at the top.
However, City have conceded the fewest top-flight goals this term (one) and the Reds have won just one of their seven games against Pep Guardiola's side in the competition.
Klopp, who has inflicted the most defeats on Guardiola in all competitions (eight), is aware of the challenge that awaits him as two title contenders face off at Anfield.
"Manchester City are for me the best team in Europe at the moment," Klopp told reporters at Friday's pre-match news conference.
"Last weekend they played Chelsea and they are good but City were clearly better that day. That's the team we face.
"We have to score, so that's been helpful but we have to defend on our highest level. We have to be brave, front-footed, cheeky in moments, really your best version and then and only then do you have a chance.
"What we did last week or the other day was okay but we need a complex football challenge.
"It's better that we don't have to boost the confidence of the players right now. Sometimes you do from time to time.
"We have a positive view but we know we haven't played City yet. We'll use the Chelsea and Paris Saint-Germain games. This is a special game."
Liverpool may boast the only unbeaten start but they were downed 4-1 the last time the two sides met in February.
However, the Reds have not lost consecutive league games against City since a run of four between 1935 and 1937 as Klopp warned that his team's start is only the beginning if they want to be successful.
"We have to defend as a unit," he continued. "It will be tricky of course and the individual quality will shine on both sides and hopefully it will be good enough for us.
"I just want to play the best season we can play. So far, so good, but it's just a few games in.
"A draw would mean we're still unbeaten. Would I take it now? It's early, let's play the game and ask me after that. So far the start is [fine] but it's not that we think we couldn't have done better.
"If we win, I'd think it was a 'proper' start. But then we play Watford, Atletico Madrid and Manchester United."