Leverkusen, meanwhile, are adamant nothing has been signed just yet.
"Bayer 04 have had a very trusting and close relationship with Florian Wirtz and his family for years," a club statement to Sky Sport reads.
"Contractual matters are discussed exclusively between the Bayer 04 management and the Wirtz family. If anything changes in the current contractual situation, Bayer 04 will of course communicate that in agreement with the Wirtz family. We ask for your understanding that we will not comment further on this topic.