Diego Simeone insists his Atletico Madrid can turn things around for their Champions League last 16 return-leg clash in Spain after suffering a shock 1-0 defeat at Bayer Leverkusen.

The Germans have one foot in the quarter-finals for the first time since reaching the 2002 Champions League final after Hakan Calhanoglu's superb second-half goal gives them a slender advantage.

Atletico finished with ten men at Leverkusen's BayArena.

Defensive midfielder Tiago was sent off for the final quarter of an hour for a second booking while centre-back Diego Godin is also suspended for the return leg after a second-half yellow card.

Simeone also has injury worries having been forced into two changes before the break when both right winger Saul Niguez and right-back Guilherme Siqueira came off injured.

"Leverkusen could have decided the match if they had scored again, so we can live with the situation and we still have a good chance at home," said Atletico coach Simeone.

"We have to be positive in the return leg, we had our chances, but it wasn't our night.

"They had us under a lot of pressure and made things hard for us.

"We didn't combine well, Leverkusen won more than their share of possession and we couldn't get our game going.

"Diego and Tiago are suspended for the return leg and we have a lot of injuries, but we still have a lot of hope."

Bayer, the 2002 Champions League finalists, edge closer to breaking their last 16 jinx having failed to pass this stage of the competition in their last three previous attempts.

Roger Schmidt's Leverkusen ended their three-match winless streak in the Bundesliga in style by stunning the 2014 finalists.

Having been humiliated 4-0 at home by Paris Saint Germain last season at the same stage, Leverkusen produced a spirited performance.

Their potent pressing game nullified the threat of Atletico striker Mario Mandzukic and attacking midfielder Antoine Griezmann, who have scored 37 goals between them this season, while replacement Fernando Torres faild to make an impact.

But Schmidt admits his side still face an up-hill task at Atletico's Vicente Calderon Stadium for the return leg on March 17.

"Nothing has been decided, but I think it was important to have not conceded a goal and we managed to subdue an attack which includes Mandzukic, Greizmann and Torres," said Schmidt, who is in his first season in charge.

"The door is still open for Atletico, but we have shown we are also good for a goal or two.

"We have to try and score in Madrid, which will really give us a chance.

"We can definitely live with the 1-0, we still have every opportunity and we see that we have a clear chance to reach the quarter-finals.

"The team did outstandingly well. They gave little away, showed a lot of maturity so the deserved winner walked off the pitch."

Leverkusen grabbed the winner when Germany winger Karim Bellarabi's back-heeled pass found Turkey international Calhanoglu, who blasted his shot from a tight angle.

"I think we were clearly the better team and therefore we deserved the win," said Calhanoglu.

"I gave it all I had for the goal, but we have to play just as well in the return leg as we did today and then we have a good chance."

Bayer goalkeeper Bernd Leno was the hosts' hero after a superb diving reflex save in the first-half to deny Tiago -- which TV pundit and ex-Germany goalkeeper Oliver Kahn described as "world-class".

"I thought it was in, then you saw Leno's hand come from nowhere to deny him. That was world-class," said an impressed Kahn.