London - Chelsea must add a new dimension to their brand of football if the champions are to mount a strong defence of the Premier League title they won in some comfort last season, says manager Jose Mourinho.
The Stamford Bridge club finished eight points clear of second-placed Manchester City in May but Mourinho said his players had to continue to evolve and could not afford to simply stand still.
"We are trying to add new qualities to our game to improve what we did in the past," the Portuguese told reporters during Chelsea's pre-season tour of the United States.
"We are trying to be a little more unpredictable because opponents know us well and we want to go to the season with high motivation.
"The title cannot give us bad things, it can only give us good things. The good things are confidence and motivation for more," said Mourinho.
Chelsea played a free-flowing style in the first half of last season but when injuries, suspensions and loss of form kicked in after Christmas they started to adopt a more cautious, pragmatic approach in order to grind out results.
Mourinho's men have been big spenders in the past but they have been almost frugal with their close-season expenditure compared to Manchester City, Manchester United and Liverpool and Mourinho said it would be a "great challenge" to try and retain the title.
While City, United and Liverpool have splashed out vast sums of money to strengthen their resources, the Londoners have merely tinkered with their squad.
Club favourites Petr Cech and Didier Drogba have moved on to pastures new and been replaced by former Stoke City goalkeeper Asmir Begovic and Monaco striker Radamel Falcao who had an indifferent spell on loan at United last season.
"I have only one objective and that is to win the next game," said Mourinho. "I have no other objective apart from trying to improve and improve and improve.
"It's a great challenge to improve our team basically without new players, apart from Begovic and Falcao. I'm more than happy with that and the players are receiving this challenge with open arms.
"Every day we work really hard to try to improve and I see great motivation in the players. They are happy because we are the same group...because myself and the club have shown loyalty to them," added Mourinho.
"We've said, 'You are the champions, you made us champions, we trust you. Even if the other clubs have made huge investment we stick with you, we believe in you'."
Chelsea, who have won the Premier League four times in 11 seasons, meet Cech's new team Arsenal in Sunday's Community Shield, the traditional curtain-raiser to the new campaign.
Mourinho's men then kick off their league fixtures with a home game against Swansea City on Aug. 8.