The need for a buy-back clause is delaying the transfer of Nigerian forward, Kelechi Iheanacho, from English Premier League side, Manchester City, to West Ham.
City insist on a buy-back clause for any deal to take place.
West Ham are bidding to sign Iheanacho for around 31 million dollars, but Man City wants a buy back clause inserted in the contract.
The Hammers are reported to want to be able to sell the player at a higher value depending on his achievement with the team.
But City do not want the situation with Chelsea in the pursuit of Romelu Lukaku, whom they sold to Everton.
Leicester City and Everton are also interested in the 20 year old Nigerian.