Xabi Alonso is looking for a big improvement from Bayer Leverkusen against fellow Champions League side RB Leipzig in the Bundesliga on Saturday. 

After a 3-2 league win at Borussia Monchengladbach, Leverkusen edged to a narrow 1-0 victory at fourth-tier FC Carl Zeiss Jena in the first round of the DFB-Pokal on Tuesday.

Despite winning their opening two games of the season, and maintaining their impressive unbeaten streak, Alonso said his double-winning side are far from their best selves.

"We know that we can play better and have not yet reached our top level yet. We need to work on that," Alonso told reporters on Friday.

"That's why we want to carry on working. It's a process to achieve that level, but it's our aim, and we're focused on that. And I'm confident we can do it too.

"The players know exactly what they have to do. We have a good flow in our game, and we have to maintain that so that we can work both with and without the ball."

Leverkusen and Leipzig will both play Liverpool, Inter and Atletico Madrid in the revamped Champions League, with Alonso conceding that Saturday's match could be a test of his side's potential in that competition.

"The game with Leipzig is a top match at Champions League level. They are very good opponents with very strong individual and collective quality and a great coach [Marco Rose]."

"We have eight great opponents, and it will for sure be intense, and obviously I am looking forward to going back to Anfield."

Leverkusen captain Lukas Hradecky has been ruled out due to illness and will be replaced by Matej Kovar in goal, Alonso also confirmed.