Werder Bremen are interested in re-signing Southampton defender Jannik Vestergaard in the January transfer window, according to Sky in Germany.
Vestergaard played for the Bundesliga side between 2015 and 2016, following a move from TSG Hoffenheim.
He made 54 appearances for the club during that time, prior to a two-season spell at Borussia Monchengladbach.
The Danish international then joined Southampton in 2018 for £18m after being involved in his country's FIFA World Cup campaign.
Vestergaard has featured 11 times for Ralph Hasenhuttl's side in the top-flight this term.
He last played in Southampton's 2-1 defeat to Everton on November 9 but has been named among the substitutes for their last four Premier League games.
The centre-back's current deal at St Mary's runs until June 2022.