Watford are scrambling to sign Schalke fullback Dennis Aogo.
The defender, off contract in June, was expected to join Watford on a Bosman deal this summer.
However, BILD says Hoffenheim are now threatening Watford's plans, where coach Julian Nagelsmann has spoken personally with Aogo.
Aogo insists nothing has been decided as he trains with Fortuna Dusseldorf's reserve team this week.
"I just want to keep fit as much as possible during my holiday," he said, without addressing his transfer plans.