Mainz insist that young teenage striker Andre Schurrle will be staying at the club for the foreseeable future.
The 19-year-old hotshot was been linked with Bundesliga champions Bayern Munich and English giants Manchester United, while Hoffenheim and Bayer Leverkusen failed to land the youngster this summer, with BILD reporting that Hoffenheim were unsuccessful with a £8.2million bid.
But Mainz's general manager Christian Heidel has reminded Schurrle's suitors that he is under contract beyond the end of this season.
Schurrle is contracted to Mainz until June 2013 so Heidel claims the Bundesliga club do not fear their prize asset being poached any time soon.
"The transfer window is shut - that's a fact and no Bayern Munich or Manchester United can change that," he told BILD.
"We have not had any enquiries from those clubs and we have a contract (with Schurrle) so we are extremely relaxed about this."
Schurrle started out at hometown club Ludwigshafen before signing a four-year deal with Mainz last summer.
He made his Bundesliga debut as Mainz finished ninth last season and went on to establish himself as a first-team regular, scoring five goals in 33 league matches, which included 25 starts.
The Germany U21 international has scored one goal from one substitute appearance so far this term - the equaliser as Mainz came from 3-0 down to beat Wolfsburg 4-3 two weeks ago.