Mainz face a battle to keep hold of Jean-Philippe Mateta this January.
Mateta is the club's top scorer this season and his form is attracting Premier League interest.
BILD says Southampton and Tottenham are both keen, with a winter market departure a possibility.
Mateta has a contract to 2023 without a buyout clause.
Mainz would be prepared to sell Mateta in January for around 30m.
