Didier Drogba scored the Chelsea winner against Barcelona in the first leg

Barcelona: FC Barcelona knew it would be tough to defend its Champions League title, just not this early in the season. Barcelona hosts Chelsea on Tuesday, two weeks after the 1-0 defeat at Stamford Bridge left the Catalans five points behind their London rivals.

With Barcelona stuck on four points in Group A — along with Werder Bremen — the Spanish champions are finding it harder than expected in a group that was seen as a two-team race with Chelsea.

Only two teams advance to the last 16 from each group. A win for Chelsea will put the Blues through to the knockout stage. For Barcelona, a loss — along with Bremen beating last-place Levski Sofia — could leave the Spanish powerhouse in real danger of elimination.

“Defeating Barcelona was vital and has given our confidence a real boost, especially as we played such good football,” Chelsea midfielder Michael Ballack said. “Every season you have two or three very special matches and this one against Barcelona was one of them. If you win such a crucial clash, the boost is tremendous.”

While Barcelona top the Spanish league, Frank Rijkaard’s side flopped in London, with the English champions dominating and effectively taking star forward Ronaldinho out of the match. “We have played them several times and know how they play,” Rijkaard told a British radio. “They are not as quick as they were two years ago in counter-attacking but they are very solid, consistent, strong and well-organised.”

The addition of Germany international Ballack has changed Chelsea’s playing style. “They are playing in a different way with Michael Ballack in midfield,” Rijkaard said.

“He is closer to the goal of the opponents. It is a little bit different and when they don’t have the ball they are well-organised and give away little space.”

Didier Drogba, who scored the Blues’ winner two weeks ago, and Andriy Shevchenko both travelled with the squad despite injury worries. Shevchenko has fond memories of the Camp Nou.

A 21-year-old Shevchenko scored a hattrick for Dynamo Kiev to help knock Barcelona to the bottom of its Champions League group eight seasons ago. “It’s a wonderful memory,” the Ukraine striker said. “The public in the Nou Camp were waving white handkerchiefs for Barcelona and applauding the Ukraine team.”

Barcelona also have injury problems for its strikers. Samuel Eto’’s knee injury has ruled him out of the remaining group stage games, while Argentine forward Lionel Messi hasn’t played since hurting his ankle in a 0-2 loss at Real Madrid last week. “The pressure on us is much less as we beat Barcelona in the first leg,” Ballack said. “Now the pressure is on them and it will be hard for them to reach the next stage.”

This is the third year in a row that Chelsea and Barcelona have met in the Champions League. Chelsea ousted Barcelona in the first knockout stage two seasons ago, and the outcome was reversed last year when the Spanish club won at Stamford Bridge on the way to capturing the title.

The meetings have been packed with red cards, disputed goals, penalties and verbal outbursts. But Rijkaard claims he holds no ill feeling toward Chelsea’s Jose Mourinho.

“I have always thought he was a great coach and I respect the way he is working,” he said. “I have never had any problems with him. If you have his kind or personality you have to follow it and stay close to your own mission, your own way. He has been very successful with it. I can only be respectful toward him.”