Chelsea and Ghana midfielder Michael Essien will be out of action for up to six weeks after returning from the CAF Africa Cup of Nations with a knee injury, his club announced on Friday.

The 27-year-old damaged cartilage while training in Angola and although the injury has not proved as serious as first feared, he is unlikely to return before early March. "He had a tear in the meniscus, and he has to stay out for four to six weeks," Chelsea manager Carlo Ancelotti revealed. "I hope four."

The lay-off means Essien will miss Chelsea's potentially pivotal English Premier League meeting with Arsenal and the first leg of the club's UEFA Champions League second round tie against Inter Milan in Italy.

An ankle problem has meanwhile ruled Ashley Cole out of Chelsea's FA Cup fourth round tie at Championship side Preston on Saturday. Yury Zhirkov will deputise while Hilario will get a rare start in goal with Petr Cech rested for the meeting with opponents struggling in the bottom half of the Championship.

He had a tear in the meniscus, and he has to stay out for four to six weeks. I hope four.
Carlo Ancelotti on Michael Essien's injury

Ancelotti also confirmed that he planned to rest Joe Cole, who is reportedly contemplating a move away from Stamford Bridge because of frustration over his lack of first-team chances. The England midfielder's current contract at Stamford Bridge expires in the summer and talks over a new deal have yet to reach a conclusion, but Ancelotti said he was confident Cole, 28, would stay.

"I don't have any news on his contract but he will stay at Chelsea next year," the Italian said. "I'm 100 percent clear. "It's the aim of the club to keep him in the squad because Joe Cole is an important player, a very professional player, he has a lot of quality and is young."

Ancelotti expects Preston manager Darren Ferguson to have taken advice from his father, Sir Alex, over how to play Chelsea, and he admitted that Manchester United's third round exit at the hands of Leeds should serve as a reminder to his side not to take victory for granted.

"I don't know Darren," Ancelotti said. "It's a good reason to meet him tomorrow. I think it's possible he'll ask his father about us. Like a father, Alex can give him some advice or opinion about our play. That's normal. I don't know Preston very well, but I'm sure they will try to do hard work on the pitch and try to do the best.

"Because the FA Cup is the oldest competition in the world, I think that every team, also the small teams, want to do their best in this competition," the coach added. "The FA Cup is a very important competition here. There were strange results in the last round and we don't want to have a strange result in this round. It's an important aim for this season and we have to try to win."