Champions League: Monaco stuns Arsenal, Leverkusen upsets Atletico

Atletico Madrid's coach Diego Simeone gestures during the Champions League round of 16, first leg soccer match against Bayer Leverkusen, in Leverkusen, Feb 25, 2015. [Photo/Agencies]

For Atletico, who were left with 10 men when Tiago was sent off following a second booking in the 76th minute, it was only their second loss in a Champions League away game since September 2013.

The Spanish champions will also be missing key defender Diego Godin for the return leg after the Uruguayan was booked and will be suspended in Madrid.

"They play as they do and they do it well," said Atletico coach Diego Simeone.

"We each had a clear chance and they took theirs and we didn't. It could have been a worse result. But I am confident for the return leg."