Filip Kostic, who made the move to Fenerbahçe from Juventus with an option to purchase, has caught the eye of Union Berlin. The German club is keen on bringing the Serbian footballer back to the Bundesliga. However, they would need to pay a transfer fee of 6 million Euros, the amount set by Fenerbahçe's purchase option, to facilitate this transfer. Union Berlin is looking to bolster their left flank with Kostic, but sources indicate that meeting this financial requirement might be challenging for the club at present. Kostic, who missed inclusion in Fenerbahçe's UEFA Europa League squad due to the timing of his transfer, has participated in 14 Süper Lig matches this season, scoring once and providing three assists. The interest from Union Berlin arises as Kostic is already well-regarded in Germany, having joined Stuttgart from Groningen in 2014 and later playing for Eintracht Frankfurt before his 24 million Euro transfer to Juventus in the summer of 2022.