Bayer Leverkusen 1-3 Barcelona
Alexis Sanchez hit his first Champions League goals, and Lionel Messi added a third, as Barcelona won their last-16 tie first leg at Bayer Leverkusen.
Sanchez capped a dominant first half for the defending champions by slotting home from the brilliant Messi's pass.
Michal Kadlec equalised with a header from Vedran Corluka's cross but Sanchez rounded Bernd Leno to tap in and restore his side's advantage.
Messi shot against the post before sealing the victory with a volley.
A comfortable win with three away goals puts Barca in a commanding position going into the second leg at home on 7 March.
Leverkusen will need a huge upset in the Nou Camp if they are to reach the last eight for the first time since making the 2002 final.
Despite drawing level shortly after half-time, they were outclassed overall and it took some dogged defending to keep the scoreline respectable.
- Barcelona had 72% possession according to Uefa
Saturday's defeat at Osasuna left Barca 10 points behind Real Madrid with their hopes of a fourth straight Spanish title hanging by a thread.
That placed even greater significance on their quest to become the first back-to-back winners of the Champions League.
But if the Catalans were beginning to feel the pressure they did a good job of hiding it against out-of-form Leverkusen.
The hosts had won just one of their previous seven matches and it was plain to see why in a one-sided first half.
Still without top-scorer Eren Derdiyok, winger Sidney Sam and experienced midfielder Michael Ballack, Bayer's lack of attacking options enabled Barca to camp in opposition territory.
Pep Guardiola's men served notice of their threat on 12 minutes as a low Sanchez cross was brilliantly intercepted by Daniel Schwaab with Messi waiting to pounce.
The German side were not so fortunate when Messi sent Sanchez clear and he finished coolly through Leno's legs.
Barca ended the half with 78% of possession, while Bayer managed no attempts on goal, no corners and were not once flagged offside.
However, it was case of roles reversed at the start of the second period as the hosts got forward in numbers and at last tested Barca's back line.
Manuel Friedrich poked wide to raise the noise levels inside BayArena, and the home side were level when Kadlec powerfully converted Corluka's centre.
Robin Dutt's side now believed in an unlikely victory, but they were brought back down to earth when Sanchez collected Sergio Busquets's through ball and rounded Leno before slotting home.
Chances were coming and going for both teams - Gonzalo Castro drilled against a post after a flowing Bayer move, while Messi was also thwarted by the woodwork following a fine run and dink over Leno.
Substitute Stefan Kiessling headed at Victor Valdes as Bayer pushed for another equaliser, but Messi settled the contest by meeting a Dani Alves cross with a calm volley.