West Ham United have rejected a first bid from Arsenal for Declan Rice.
The London Evening Standard says the non-disclosed offer falls short of West Ham's valuation and there was also disagreement over method of payment.
Arsenal's opening included a series of bonuses.
West Ham are demanding £100m to part with their captain, who has made it clear joining Arsenal is his priority.
Arsenal have been warned by intermediaries they could face competition from Manchester City, which are currently considering jumping into the battle.