One of those ten derbies this season, at White Hart Lane, may well be seen as the game when the Premiership title began slipping away from Chelsea. The pyrotechnics on 5 November not only included a red card for John Terry and Tottenham's first League victory over Chelsea in 33 attempts, but allowed United to celebrate Alex Ferguson's 20th anniversary as manager by moving three points clear at the top. They have stayed there ever since.

Now, as the Premiership pauses for FA Cup quarterfinal weekend, comes another derby and the chance for revenge on Spurs, this time at Stamford Bridge. It is a chance Chelsea will be expected to take and one Ballack can use to build on the self-belief he gained from his decisive goal against Porto.

It has been a mystery how a pivotal figure for Bayern Munich and Germany could have made so little impression this season. Admittedly, the same was said of Andriy Shevchenko until a flurry of goals in cup competitions and an improved work ethic restored both Shevchenko's confidence and Chelsea's in him. Will Tuesday's sweetly volleyed goal do the same for Ballack?

Speaking after the game, he did not look like a man struggling for self-assurance, his smile widening when asked if he was happy with his game: "No, not super-happy!

I can play better, I know that.

I have to improve my game.

But it's not easy when you go to a big club, where they won two League titles, they know the style and you come into a winning team. But I wanted the challenge here. For me it was the same situation at Bayern Munich, we won and I wanted to change my experience. So it's not easy at the beginning but I think the future will be better."

Tottenham's visit to Stamford Bridge brings comparisons with a former team-mate at Bayer Leverkusen, Dimitar Berbatov, the Bulgarian who has eased himself into English football.

"For him it goes faster than for me, " Ballack admitted. "I know he's a good player and is doing well at Tottenham because he scores a lot of goals. I'm happy for him, he's a good guy and I think the fans love him. Maybe it's a little bit easier for a striker.

But it's different clubs, everything is different, so you can't compare the situation. We have other expectations at Chelsea than at Tottenham."

Robben completed 100 games for the club on Tuesday but has yet to win the FA Cup. "It's a big prize in England with a lot of history, " he said. "We have won the Carling Cup and League twice but not the FA Cup and we want it.

"This is a special season, " Robben said. "There is pressure to win but it is enjoyable, that is why we are all at Chelsea. Now we have to step up as a team. We have had some bad games and lost points in the League but we must keep winning games.

The dream is to win all four competitions. The League will be difficult but it is not over and we'll keep fighting.

We have won one trophy and we are two steps away from the final in two more cups and we can do it. The critics have said we are not playing particularly well but if we win the Carling Cup, the FA Cup, the Premiership and the Champions League, then I think that will answer them."