Ashley Cole today told his Chelsea team-mates they have to cut out the defensive mistakes and win their last seven League games if they are to have a hope of winning the Premier League.

Chelsea kept their hopes alive with a 2-1 win over Arsenal last week to stay within five points of Manchester United but Cole still fears they may still end up second best.

Avram Grant's men have conceded five goals in their last two League games with four of them coming from set pieces, which has proved their weakness for most of the season. Cole insisted the improvement will have to start against Middlesbrough at home on Sunday.

He said: "It's going to be tough to win the championship. We may have to win all of our games and hope United drop points, but it wasn't long ago we weren't even in contention, according to some people.

"We are disappointed with the number of goals we are conceding from set pieces considering the people we have at the back. Maybe it's a lack of concentration."

Meanwhile, Mike Riley will not be in charge of a Premier League fixture this weekend.

The referee appears to have paid the price for the controversial part he played in Chelsea's fiery 4-4 draw with Tottenham at White Hart Lane, when he failed to send off Cole after a horror challenge on Alan Hutton and the dissent that followed.

Riley will referee the Championship fixture between Charlton and Wolves on Saturday.