Ahead of Aston Villa's crunch clash with Chelsea this weekend, Stiliyan Petrov has suggested that the Stamford Bridge club have been on the slide ever since Jose Mourinho vacated the hot-seat.

The 29-year-old said in The Guardian, "When Mourinho was there they had a special team. I think they had more belief in themselves.

"I don't think Chelsea are the team that they used to be under Mourinho. A lot of changes have happened there."

Indeed, the Blues have not won a trophy since the Portuguese boss, now at Inter, left the club in September 2007 following a long-running dispute with owner Roman Abramovich.

The Londoners currently sit fourth in the Premier League table, two points behind third-placed Villa, and Petrov knows they will be fired up for their trip to the Midlands.

"They'll come here and be strong," the Bulgarian international said. "They have a new manager [Guus Hiddink] and every new manager wants to start with a win, so we are expecting a hard game.

"They'll try to show that they can still be at the top, but we'll try to show them that what we have achieved so far is not just because of luck but because we've been playing well."