James Milner's move to Manchester City is being held up by Stephen Ireland's demand for a £2m payment to leave Eastlands, BBC Sport understands.City have offered Aston Villa £18m for England midfielder Milner, 24, with Ireland moving in the opposite direction as part of the deal.
But Ireland is understood to be insisting on receiving £2m from City, a sum the club are unwilling to pay.
The Milner deal is unlikely to go through until the issue is resolved.
Milner has been linked with a move to big-spending City for most of the summer, with former Villa boss Martin O'Neill - before his departure on Monday - admitting he was resigned to losing the player.
City, who are backed by the riches of Sheikh Mansour, had hoped to complete the signing by Thursday 12 August but the issue could now drag on.
"City have no intentions of backing down in the face of Irelands's demands," said BBC Radio 5 live correspondent Pat Murphy.
Do you think the deal will go through?
"They feel that too many clubs are trying to take advantage of their vast riches and that £2m is a ridiculous sum to dispense with a player who didn't feature much last season and is not in Roberto Mancini's future plans.
"City also believe that Ireland is simply not entitled to £2m to leave. If no compromise can be reached then the Milner deal is shelved for the time being.
"City have given no indication that they will go beyond the £20m they offered Villa in May, so the only deal on the table is £18m plus Stephen Ireland."
Ireland, 23, is a product of City's academy and made his debut for the club in 2005.
But the influx of new players since City's wealthy owner took over the club in 2009 has seen Ireland drop down the pecking order.
The Republic of Ireland international, who is contracted at Eastlands until the end of the 2013-14 season, made 30 appearances for the club in 2009-10.
Former Leeds and Newcastle midfielder Milner joined Villa for £12m in 2008 and has developed into a regular England international since joining the club.
Source: BBC Sport
Source: BBC Sport