Chelsea stars John Terry and Frank Lampard are determined to ensure their contract problems do not overshadow the club's fight for more success this season.

Captain Terry and England midfielder Lampard are trying to negotiate long-term extensions to their current contracts and want their respective situations resolved as soon as possible.

The club have yet to make a formal offer to Lampard while Terry is unhappy with the length of the contract put on the table by the club.

Talks have been dragging on for months and the delay has sparked fresh speculation that they could quit the club in the summer.

On Monday, Chelsea's Ghanaian midfielder Michael Essien signed a new five-year extension worth around £90,000-a-week to the African player and Lampard is keen to ensure that the loyalty shown to the club by him and Terry is not taken for granted.

Lampard said: "If there are any two players who have got the best interests of this club in their hearts it is me and John. The club know that.

"The contract situation is not a distraction and it is important it doesn't get talked about too much.

"Me and John don't like to see it and the fans don't like to see it."

However, both players are now reaching the final two years of their Stamford Bridge deals and want to stay.

However, they want the same pay parity as top earners Michael Ballack and Andriy Shevchenko - both reported to be earning around £130,000-a-week.

Lampard, 28, may well be in a position to buy himself out of the club in the summer under FIFA rules.

But Terry cannot do the same and the Blues captain, fit again after the head injury he sustained against in the Carling Cup final against Arsenal, is unhappy with Chelsea's decision to reduce the length of their offer from nine years to five.

However, despite continuing concerns over their futures, both coach Jose Mourinho and chief-executive Peter Kenyon insist the pair will be at Stamford Bridge for years.

Kenyon said: "We are confident the important players will be here for many years to come."

Chelsea's injury problems continue to dog their season and the latest blow occurred on the training pitch when Shevchenko limped out of action towards the end of Tuesday's session.

The Ukrainian captain appeared to hurt his left ankle as a result of a tackle and immediately left the session for treatment.

Chelsea were still assessing the injury as they boarded the coach for the trip to Manchester.

Shevchenko is now a major doubt for Wednesday night's clash against Stuart Pearce's struggling City side and Mourinho may also opt to rest a few of his other stars including Ricardo Carvalho, Ballack and Didier Drogba.

Ballack has struggled to find his best form since joining the club on a free transfer from Bayern Munich last summer.

But Mourinho insists the Germany captain, criticised by sections of the club's fans, remains a pivotal part of the Chelsea side.

Ballack went a long way to silencing the doubters with the tie-winning goal against Porto in the last 16 of the Champions League, but admits Chelsea are not playing at their best level yet.

Ballack said: "We are all good players individually but we play better as a team. Individually we are very strong but at the moment we're still not playing at our top level.

"I think there is more to come - we can still improve and do better."

He also denies that he has found it difficult to adapt to English football despite the criticism from a number of fans.

He added: "It is my first time here in England but I am not finding it a problem and I'm feeling fine.

"I had no break in the winter and that can be tough. But there are no problems - I feel really good."

Ballack also suggests that numerous big games in quick succession is good for their chances of doing well in their remaining three competitions.

Chelsea will reduce Manchester United's lead to six points at the top of the Barclays Premiership if they can beat City and Ballack added: "My experience tells me that after a big game, it's good to have another one straight away because you can maintain the momentum.

"It's what great teams have to do - they have to live with this situation.

"Sometimes if you have maybe a less important game following a big match, you can come down a little. But big games keep the motivation levels high."