Niklas Sule has offered his support to Borussia Dortmund team-mate Sebastien Haller after he discovered a testicular tumour, insisting on-pitch matters are "one hundred per cent in the background" while he recovers.

Haller, a new signing at Dortmund, was forced to leave the club's pre-season training camp in Switzerland after feeling unwell on Monday, with subsequent tests revealing the tumour.

Dortmund boss Edin Terzic then revealed the striker had returned to Germany for further tests, describing the news as "brutally difficult".

Haller's former Ajax and Utrecht coach Erik ten Hag was among those to wish the Ivory Coast international a speedy recovery yesterday, sentiments which have now been echoed by fellow Dortmund new boy Sule.

"The sporting aspect is one hundred per cent in the background," the defender told Dortmund's media channels. "It is the man Sebastien Haller that we miss. 

"We wish him all the best, that he gets well again quickly and a lot of strength for the time that will come now. 

"How he handled the news was very positive. As a team, we wanted to give him a small sign that we were with him. I wish that he will get well very soon."

Sule agreed to join Dortmund upon the expiration of his contact with Bayern Munich back in February, and made the switch in July after winning five Bundesliga titles and one Champions League with the Bavarian giants.

But the towering defender, who contributed to five clean sheets in 22 league appearances last season, believes his new club are more than capable of ending Bayern's 10-year stranglehold on the Bundesliga title.

"I didn't come here because I don't believe in winning the league with this team," he added. 

"I strongly believe we can do that. We have a lot of quality in my opinion, and we will do everything not just verbally but hopefully also on the pitch to be able to reach that objective."

Asked whether winning the Bundesliga would mean more at Dortmund than it did with Bayern, Sule responded: "I can't say that right now. I know what it felt like winning the titles with Bayern. 

"And if this would be more beautiful, then I'm happy."