Fortuna Dusseldorf are hoping to sign Dodi Lukebakio permanently.
The Belgian striker has impressed in the Bundesliga, netting 12 goals and managing five assists this season.
He had standout games against Bayern Munich and Borussia Dortmund, the league's two top teams.
According to Bild, Fortuna want to get him permanently in the summer.
But it is unclear how Watford want to proceed, as they could want to add Lukebakio into their squad for next season.
Afee around six or seven million euros could be a possible starting point.