Allofs revealed the Bundesliga club are ready to make significant signings in the New Year and will pursue Premier League players should they become available.
"At Werder (Bremen), I have seen just how good de Bruyne is, and at Dortmund we have seen how well Kagawa can do."
"We want to do reasonable transfers, just like with Luiz Gustavo," he is quoted as saying by Bild.
"That was exceptional in terms of transfer fee and dimension.
"We want to continue a selective reinforcement of our squad. Not in a heave-ho style."
"If such players are possible, you of course think about them.
"But we should not raise the hopes of our fans. In the end they comment: 'Once again, you failed to sign him'."
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