Borussia Dortmund lost 1-0 at Borussia Mönchengladbach on Sunday in a flat performance that has intensified questions about Kovac's style of play and his willingness to integrate young players into the squad.
Gladbach secured their Bundesliga status with the win, while Dortmund — who remain second in the table and are already qualified for next season's Champions League — cut a frustrated figure on a day when the stakes were clearly far higher for the hosts.
According to Ruhr Nachrichten, Dortmund's hierarchy intend to meet with Kovac's management imminently to begin discussions on extending his contract beyond its current June 2027 expiry. The aim, as described by the club, is to extinguish the growing coaching speculation before it can gather further momentum.
Bild added that Kovac himself is keen to remain in Dortmund and that approaches from England — including from Manchester United, Chelsea and Tottenham Hotspur — are not being considered at this stage.
Book, who replaced Sebastian Kehl as sporting director earlier this season, was unambiguous in his public positioning.
"We have already clearly expressed our confidence in Niko. I really, really enjoy working with him. I was asked about this even before today's match and spoke very positively about it. The defeat has certainly not changed that in any way."
Kovac's own post-match assessment of the Gladbach loss was direct.
"That was not a good performance. Gladbach were sharp, aggressive and fierce — you could see how much was at stake for them. We didn't match that intensity and didn't hold our own physically."
Kovac has been in charge since February 2025, when he replaced the sacked Nuri Sahin. In that time he has averaged 1.94 points per Bundesliga game, guided the club back into the Champions League and added the DFB-Pokal to the trophy cabinet last season. Two persistent criticisms have followed him throughout — a reluctance to use academy players in meaningful minutes and a pragmatic style of football that divides opinion among the support.
The renewal talks, when they begin, are expected to reflect both parties' desire for a longer-term project. Dortmund believe the instability that has dogged their coaching situation over recent seasons — four permanent appointments in three years before Kovac — is damaging, and they see continuity as the foundation for progress.