Chelsea ace Juan Mata says they must get mentally tougher.

Mata, the £23.5million summer signing, has been one of the few Stamford Bridge successes this season.

He said: "The whole squad is not content with our game at the moment.

"We are not functioning well enough in the Premier League and we need a quick reaction. That is our main objective. It's normal that the manager (Villas-Boas) is not happy with the performances, but we know we can still improve on the pitch.

"You can never say anything is impossible in football. But at the moment the gap is too big between us and the Manchester clubs. There's too many points.

"We need to reduce the gap on Spurs but to do that we need to keep winning - just win, win and win."