Hakan Calhanoglu scored the only goal of a game dominated by the hosts, who ended the match with an extra man after Tiago was sent off. He will miss the second leg, which Roger Schmidt's men will look forward to with confidence after a stirring display.
Leverkusen had the bit between their teeth as they came out with no fear against last season's beaten finalists. Early on Calhanoglu advanced confidently with the ball and fed Lars Bender, who seemed to be caught in two minds as to whether to shoot or pass, and the result was something in between. Soon after, Wendell's shot found its way to Emir Spahic, whose effort was cleared off the line by Mario Mandzukic.
Leverkusen's growing pressure led to Spahic striking the crossbar with a 30-yard effort that had visiting keeper Miguel Angel Moya well beaten, before the guests almost snatched the lead against the run of play. Antoine Griezmann seemed to wait an age for the ball to drop so he could nod in from a yard out, but Bernd Leno had other ideas as he scampered across his goal to push the ball away. Leno then excelled himself again to deny Tiago at the conclusion of an intense opening 45 minutes.
Tiago sees red
There was no let-up in the second half, thanks in to the tireless running of Karim Bellarabi. The Germany international ran the Atletico defence ragged on numerous occasions, eventually teeing up Calhanoglu to drill his shot into the roof of the net and give Bayer the lead. Diego Godin picked up a costly yellow card in trying to stop Leverkusen's next advance, also earning him a suspension for the return leg, and worse was to follow for the Spanish champions.
After Josip Drmic had wasted a good chance to increase Leverkusen's lead and Fernando Torres had a goal ruled out at the other end, Tiago was dismissed for a second yellow card. Stefan Kießling was sent on as Leverkusen went for the jugular, and although they were unable to make their extra man count, they will nevertheless travel to the Vicente Calderon optimistic of finishing the job after sending out a clear signal of their intent in Europe at the BayArena.
Leverkusen: Leno - Spahic, Hilbert, Papadopoulos, Wendell - Bender (Rolfes, 67'), Calhanoglu (Brandt, 87') - Castro, Bellarabi, Son - Drmic (Kießling, 80')
Atletico: Moya - Godin, Siqueira (Gamez, 38'), Juanfran, Miranda - Tiago, Gabi - Griezmann, Saul Niguez (Raul Garcia, 42'), Arda Turan (Torres, 64') - Mandzukic
Goals: 1-0 Calhanoglu (57')
Red cards: Tiago (76')