Chelsea midfielder John Obi Mikel has admitted that his side need to improve if they are to gain a result against Manchester United on Sunday.

The European champions slumped to a 2-1 defeat to Shakhtar Donetsk on Tuesday night, and Mikel has acknowledged that he hopes the club can avoid a repeat of previous seasons where a lack of form during the winter months has cost them the opportunity to compete for the Premier League title.

Mikel said: "All of us know what has happened in recent seasons, so we have to make sure that the Shakhtar defeat doesn't make that happen again.

"We have to make sure we correct it very quickly and that starts with the next game against United.

"They will be very dangerous as usual and, if we defend the way we did against Shakhtar, it's going to be difficult for us. We have to defend as a unit, play together as a unit. As long as we do that on Sunday, we'll have a very good chance."

Mikel joined Chelsea in 2005 after rejecting a move to Old Trafford.