Karim Adeyemi is upbeat that Borussia Dortmund can overcome the indefinite absence of fellow forward Sebastien Haller who has been diagnosed with a testicular tumour.

Adeyemi, like Haller newly signed by Dortmund, said Thursday at their pre-season training camp in Switzerland that “we will try to continue playing football.

“Maybe with a different formation or with someone else in attack. In the end we have the quality to play with another striker,” Adeyemi said.

Haller was to take the place of Erling Haaland, who has moved on to Manchester City, after his arrival a few weeks ago from Ajax Amsterdam.

But he was on Monday diagnosed with the tumour after feeling unwell during training. He was to undergo further examinations but Dortmund have no further statements.

Germany winger Adeyemi said he doesn’t expect a stuttering start into the season over Haller’s absence.

Dortmund start next week Friday with a German Cup match at third-tier 1860 Munich and their first Bundesliga match is a week later against Bayer Leverkusen.

“I am looking forward to start into the season with such a great team. We want to start in dominant fashion and show the other teams how to defend,” said the 20-year-old who came to Dortmund from Salzburg.

“It is my role to create unrest with my speed.”

Adeyemi also wants to do well in Dortmund in order to make the German squad. He made his national team debut last year but has only played five minutes in the recent four Nations League games.

“Karim must show a development and take the next step at Dortmund,” Germany coach hansi Flick has said.