Lionel Messi fired the home side ahead on nine minutes, and Samuel Eto'o doubled the lead three minutes later.

Messi netted his second seven minutes from the break and Thierry Henry completed the rout on 43 minutes.

The German side were clearly downcast, following their 5-1 drubbing at Wolfsburg on Saturday in the Bundesliga.

Their lack of firepower also affected their performance, with Luca Toni playing as a lone striker after Miroslav Klose was kept on the sidelines due to injury.

Conversely, the Catalans were boosted by a host of domestic victories throughout the past few weeks, and Messi, Eto'o and Henry were definitely at their best.

With the emphatic victory, Barcelona have almost guaranteed a semi-final berth, as seemingly the German champions won't have much of a chance in the second leg.

Dominance

Barca exerted notable dominance over their opponents right from the start.

Henry was about to open the scoring only after six minutes, but his effort was cleared off the line by Martin Demichelis.

Bayern's backline was completely helpless while the hosts were piling up pressure upfront, looking for their first goal.

Messi hit the opener with aplomb after being set up by Eto'o, hence the Spanish giants took full control of the game.

On 12 minutes, it was the other way around when Cameroonian ace Eto'o was fed by Messi to add the second with a magnificent clinical finish.

Five minutes later, Messi could have earned a deserved spot-kick when he was felled by Christian Lell in the box, but the referee booked the 21-year-old instead.

France's Henry posed a great deal of threat on many occasions, and his deft assist enabled Messi to add Barcelona's third.

The former whipped in a left low cross that found Messi, who tucked it home after outstretching his right leg.

On 43 minutes, Henry translated his efforts and scored a fourth goal with a low drive.

Iniesta was about to poke another goal in the dying minutes of the first-half, but his point-blank effort missed the target.

Josep Guardiola's men kept the upper hand in the second period, which was much less eventful than the first.

Messi was close to completing a hat-trick, but his shot was pushed onto the post by Bayern goalie Hans-Jorg Butt.

Ze Roberto tried to score the consolation goal for the away team, but a last-gasp Carles Puyol tackle prevented him.

Iniesta and Messi came close minutes before the final whistle, but couldn't embarrass Jurgen Klinsmann's side any further.