Liverpool manager Jurgen Klopp has highlighted the threat posed by Chelsea, ahead of Friday's highly-anticipated Premier League clash at Stamford Bridge.
The Blues have made a strong start to the Premier League campaign under newly-appointed manager Antonio Conte, recording three wins and one draw.
Striker Diego Costa, in particular, has played a key role in Chelsea's unbeaten start, scoring four times and providing one assist.
When asked for his thoughts on Costa, Klopp said: "He's world class. If other supporters love you that's not a good sign. He's a warrior on the pitch."
However, Klopp also pointed to threat posed by Eden Hazard, who almost single-handedly steered the Blues to victory over Liverpool in the second half of last season.
"Hazard was outstanding at Anfield last season but we didn't defend against him too well. We will have to do better," added.
"Oscar, Willian, what a player, Matic, they brought in Kante & Luiz… It's a challenge but I feel good when I think about it."
Liverpool have also started the season well, and recorded a memorable 4-1 victory over defending Premier League champions Leicester City last time out.
But Klopp is refusing to rest on his laurels, claiming their is still room for improvement.
"There is still space for improvement and we need to improve for the Chelsea game," continued. "They have so much experience. We are much younger.
"We are the challenger and we want to create problems for them."