Following Tuesday's impressive away performances from Barcelona and PSG, it was again the visitors that came out on top in the last-16 first-leg clashes.
Bundesliga leader Bayern Munich made Arsenal pay for not taking advantage of a penalty in the eighth minute while Atletico Madrid rode the storm at San Siro and came away with a vital away goal thanks to Diego Costa in the second batch of last-16 encounters.
Goal selects the best imagery from the Wednesday's fixtures as Diego Simeone and Pep Guardiola saw their teams close in on the quarterfinals.
Champions League icon Clarence Seedorf faced his first game in Europe as coach of AC Milan
The seven-time European Cup winners anticipate a strong home performance
To the frustration of the home support, Atletico Madrid goalkeeper Thibaut Courtois keeps Milan at bay
A rare chance for Atleti falls to Diego Costa, but his audacious overhead kick fails to break the deadlock
But the Spaniards' top scorer eventually finds the net with a far-post header seven minutes from time
Deigo Costa roars into celebration after heading home a vital away goal for Atletico Madrid
At the Emirates, Arsenal dominates early but Wojciech Szczesny is forced into a fine save of Toni Kroos
Mesut Ozil is tripped by Jerome Boateng in the box and Arsenal is awarded a penalty
The German midfielder dusts himself off but Manuel Neuer palms away the shot with ease
In the 37th minute Arjen Robben is clattered in the area by a clumsy Wojciech Szczesny challange for a penalty
The Poland goalkeeper is shown a red card by the referee and the Gunners are reduced to 10 men
Bayern Munich fullback David Alaba steps up against Lukasz Fabianski but sees his shot hit the post
Arsenal's resolve is broken 54 minutes in when Toni Kroos bends a shot into the top corner
Two minutes from time, substitute Thomas Muller plants home a firm header from a Philipp Lahm cross
Unused substitute Bastian Schweinsteiger smiles as Bayern takes a strong advantage to Germany