Rudi Voller has claimed that Bayer Leverkusen's 1-0 victory over Atletico Madrid in the first leg of their Champions League quarter-final is a "definite achievement".

The Bundesliga outfit take a 1-0 lead to Madrid in a fortnight, thanks to Hakan Calhanoglu's strike at the BayArena.

However, while the Bayer sporting director praised the home side's focus, Voller is expecting a difficult task in the second leg.

The former Germany manager is quoted by UEFA.com as saying: "If you beat a classy side like Atletico, it's a definite achievement.

"It will be tough in the second leg, but after our latest matches [in the Bundesliga], which were difficult for us at times, we did an outstanding job today. Everyone was fully focused from the first to the last second."

Leverkusen are currently sixth in the Bundesliga table.