Borussia Dortmund are on the verge of signing Cologne striker Anthony Modeste as cover for Sebastien Haller, who is expected to be sidelined for several months after a removed testicular tumour turned out to be malignant. Haller was a headline signing from Ajax in summer but was diagnosed late last month before playing a competitive game for his new club. The much-travelled Modeste, 34, has now been found as a back-up solution according to sport chief Sebastian Kehl on Sunday. A “basic verbal agreement” has been reached, said Kehl, with Modeste’s medical and other formalities expected to be co…