Yaya Toure believes Manchester City have lost their element of surprise as a result of being crowned Premier League champions, and must become more inventive in order to retain their trophy.

The 2011-12 title winners traded blows with rivals Manchester United throughout the campaign before being crowned winners with virtually the last kick of the season, but now trail Sir Alex Ferguson’s side by four points.

And the Ivory Coast international thinks Roberto Mancini’s men must work hard on new systems and tactics in order to keep opponents guessing, or else teams will become wise to City’s weaknesses and exploit them.

“Whereas perhaps we caught a lot of teams by surprise last season, this year our opponents know how we play,” he told The Sun.

“Sometimes we have to change our system to try to break teams down. The other teams and players can analyse how we play, study our systems and styles and work out ways to stop us.

“Even sides who are near the bottom of the table are more than capable of making it difficult. A team that lost 4-0 against us last season will have learned and will change their tactics.

“They won’t want to get beaten heavily again so they will pack men behind the ball and make it difficult for us to find a way through.

“That’s why I love football. There is always a challenge and always a puzzle to try to solve – and when you get past that it’s very rewarding.

“You have to use your skill, intelligence and strength to improve and try to overcome each obstacle. In contrast, when a game is too easy, I get very bored.”

Toure even suggests the shift in tactics from other teams this year means he is now in a position to dominate games further – and he feels his side has learnt how to win the hard way ahead of a festive fixture pile-up.

He added: “I see a lot more of the ball because we have to control games whereas last year teams came to attack us. I have to stay back more now because of the threat of counter attacks.

“I think the key at this time is getting the results you need rather than how you actually play. We have to win and that means digging deep into our energy reserves because we will be tired and won’t get much rest.”