The Champions League holders now have the weight of expectation on them, having clinched an unlikely maiden European title after an under-par sixth-place finish domestically.

With big-money signings Eden Hazard (32 million pounds) and 21-year-old Brazilian Oscar (25 million) joining the club, Di Matteo, who was appointed as permanent manager in July, knows a repeat of last season won't be acceptable.

"I think expectation levels at Chelsea have always been very high so it (winning the Champions League) might have added a little bit of pressure to it but it was always so high anyway," Di Matteo said.

"It's an ambitious club and we know that we have to try and win trophies and be successful.

"I always felt very responsible for the results - the pressure is always there whether you are appointed permanently or not. When you have to lead a club like this you know it's a pressurised job."

Yet breaking the two Manchester clubs' stranglehold on the top two places won't be easy with Di Matteo hailing champions Manchester City the ones to beat, while he expects United to improve after prizing away star striker Robin Van Persie from Arsenal.

"Personally I still believe that Manchester City are the favourites because they haven't lost any key players, they have showed their strength," he said.

"But certainly (Robin) Van Persie is a good signing for Manchester United."

Chelsea's first opponent Wigan stormed home last season to avoid relegation with seven wins in their last nine games, including the scalps of Liverpool, United, Arsenal and Newcastle.

"It's definitely a difficult fixture (against Wigan)," Di Matteo admitted.

"Last season at the end they were very strong. The (nine) games they were very, very good, we played them at home and it was a difficult game for us.

"We have to expect a very difficult game on Sunday. They are playing at home as well, so it won't be easy for sure."

But following his appearance at the 2012 Olympics, Di Matteo said Oscar was unlikely to make his debut at the DW Stadium on Sunday.

"He (Oscar) has only been in the building for a day and a half. We will see, I still have to think about it for Sunday but there will be plenty of time for him to play."