Hertha Berlin new manager Jurgen Klinsmann, according to a report on fussballinfo.net, is looking to reinforce his squad during the winter transfer window to replace some of the club’s ageing stars.
Former Chelsea and Ivory Coast winger and Bosnia’s Vedad Ibisevic are expected to leave the Bundesliga side at the end of the season, with Kalu seen as one of the players suitable to help move the club forward.
Bordeaux, according the report, however face competition from LaLiga side, Real Betis, who are keen on luring the speedy star to Spain.
Kalu linked up with Bordeaux from Belgian outfit KAA Gent for around €8.5 in 2018.
The 22-year-old has featured in 37 league games for Bordeaux since arriving at the club and has scored four times.