On Tuesday, Chelsea will travel to Camp Nou to face a Barcelona side coming off one of their worst weeks in recent history.
Before their loss to Madrid on Saturday, Pep Guardiola's club had been unbeaten at home for more than 50 games.
Last Wednesday, Chelsea's Didier Drogba lifted the Chelsea over the Spanish giants by capitalizing on Lionel Messi's midfield giveaway.
Seconds before the halftime whistle, Chelsea ran a quick counterattack catching Barcelona's back four off guard. Drogba received a cross right in front of the goal and casually slid it past Victor Valdés.
By the final whistle, Barcelona had 20 more shots than Chelsea and had maintained 75 percent of possession. But these stats mean nothing without a goal.
Petr Cech was in excellent form as he turned aside shots that looked sure to find the back of the net.
Five minutes into the second half, Adriano made a scintillating run and unleashed a shot to the far post. Cech stretched out and made the save. In the closing minutes of the game, Carles Puyol headed the ball low across the face of the goal. Cech laid out to make another fingertip save.
His performance is the principal reason for Chelsea's victory. Petr Cech was the Man of the Match, and Chelsea will need a similar performance on Tuesday.
For Barcelona, it is essential to find a goal-scoring alternative to Lionel Messi, who has scored over 40 percent of their goals this season.
Chelsea gave him no space last week, and if that match was any indication for the upcoming one, the Spanish side will need another player to step up.
Early in the season, Cesc Fàbregas proved that he could be a scoring threat but has since managed fewer opportunities.
Alexis Sanchez is another option, but he lacks consistency and sometimes shoots when a pass is more appropriate.
Going into the second leg with a 1-0 lead, Chelsea will be content with a draw. They will also manage to advance if they score and only lose by one because of the away goals rule. Barcelona will want to win by two, so expect them to apply heavy pressure on Chelsea's backs.
With such a commitment to attack, Barcelona will once again be vulnerable to the counterattack. On Saturday, Real Madrid's winning goal came from a counterattack finished by Ronaldo after receiving Mesut Ozil's long pass.
Nevertheless, if Barcelona can mitigate Chelsea's height advantage on set pieces and avoid costly giveaways in the midfield, they will produce a positive result.
Although Real Madrid defeated them at home, the Catalan side rarely fails to score fewer than three goals in Camp Nou.
Expected Result: Barcelona 2, Chelsea 0.
Aggregate score: Barcelona 2, Chelsea 1