West Ham's latest transfer target is starting to become embroiled in a 'will he, won't he' saga as the East London club try to secure another big summer signing.
David Moyes has been keen to land the Serbian left wing-back's signature to strengthen a weak area of the West Ham squad, with only the ageing Aaron Cresswell and error-prone Arthur Masuaku battling for a first-team shirt.
The West Ham boss is now willing to offer Kostic a big-money pay rise after rumours emerged from the German media that the 29-year-old was willing to stay at Frankfurt and leave as a free agent at the end of the 2022/23 campaign. This would then allow him to become a more appealing free transfer prospect to Champions League clubs.
Kostic is rumoured be on around £43,000-a-week at Frankfurt, and West Ham will be considering a significant increase on that sum, especially after removing Andriy Yarmolenko's reported £100,000-a-week from the wage bill.
Kostic's agent also represents West Ham's expected new signing Gianluca Scamacca and it is believed he has remained in London to thrash out a deal with West Ham chiefs.
The potential £15million move to the London Stadium is still yet to be agreed by the two clubs, but West Ham are confident that will not be a major hurdle.
Kostic made 43 appearances across all competitions for Frankfurt in 2021/22, scoring seven goals and creating 15 assists, he also made the most key passes in the Bundesliga during the season.