Hakan Calhanoglu gave Bayer Leverkusen victory in the first leg of their Champions League last-16 tie against last year’s finalists Atletico Madrid.
Calhanoglu scored the only goal on 57 minutes, firing into the top of the net after Karim Bellarabi’s backheel.
Atletico had midfielder Tiago sent off for a foul on Bellarabi – his second booking – and had a goal ruled out.
Fernando Torres thought he had scored with a header following a corner, but the ball had already gone out of play.
The result means the tie remains in the balance ahead of the second leg at Atletico’s Vicente Calderon on 17 March.
Leverkusen have won just one of their past five Bundesliga matches and none of their previous seven Champions League knockout games.
But the German side, who finished second to Monaco in Group C, started well and nearly took the lead on 14 minutes when Emir Spahic’s header was hacked off the line by Mario Mandzukic.
Spahic, who replaced suspended Turkey international Omer Toprak in Leverkusen’s defence, beat Miguel Moya again 11 minutes later, but his 25-yard drive struck the woodwork.
Atletico, who had lost just one of their previous nine away games in the competition, were outfought for much of the first half.
But Leverkusen goalkeeper Bernd Leno was forced to tip a cross off Antoine Griezmann’s head and then pull of a wonderful save from Tiago’s volley as the interval approached.
It was the hosts who took the lead, though, as Bellarabi drove into the area and backheeled the ball into the path of Calhanoglu, who smashed home.
Atletico boss Diego Simeone, who had to make two substitutions in the first half, responded by replacing Arda Turan with former Liverpool and Chelsea striker Torres.
The Spaniard had the ball in the Leverkusen net on 74 minutes, only for his close-range header to be ruled out.
And the visitors’ hopes of a comeback were all but ended when they were reduced to 10 men moments later, with Tiago shown his second yellow card after sliding in on Bellarabi.