Borussia Dortmund striker Sebastien Haller requires chemotherapy and will be sidelined for “several months” after a removed testicular tumour turned out to be malignant. Dortmund sportsdirector Sebastian Kehl said in a club statement Saturday that Haller’s chances of a full recovery were “very good” but has also said that Dortmund are looking for a replacement. “Sebastien will now receive the best possible treatment. The chances of recovery are very good,” Kehl said. “We wish him and his family a lot of strength and optimism and our thoughts are with him in this difficult time.” Haller arrived…