David Turnbull's proposed move to Celtic is hanging in the balance after the Motherwell player's agent declined the Scottish champions' "magnificent" contract offer.
Motherwell accepted a club-record fee understood to be worth about £3million on Wednesday but talks over personal terms have broken down.
Celtic's contract remains on the table but there looks unlikely to be an improved offer.
A spokesperson for Celtic said: "Celtic was pleased to agree a record-breaking fee with Motherwell FC and we have quickly followed this up with a fantastic offer to the player through his agent.
"Currently, we have been unable to come to an agreement with the player's agent.
"Celtic is content that it has made a magnificent offer and it is now up to the agent and player to decide if the player wants to join Celtic. If not, we move on."
A Parkhead source denied earlier claims that Turnbull had undergone a Celtic medical.
Motherwell rejected a bid from Barnsley earlier in the summer but it is understood there have been no fresh offers since Wednesday's development with Celtic.
More than a dozen clubs previously asked to be informed of developments, including Manchester City, Bournemouth and Bristol City.
The 19-year-old midfielder has two years left on his Motherwell contract, which he only signed in January.
Speaking then, he said: "I can kick on now, keep getting games under my belt, keep trying to do what I'm doing and hopefully it could be the start of something.
"I think I've made a decent start, but I know I've got a lot to learn and the place for me to do that is at Motherwell."
Turnbull joined his boyhood club at the age of nine and enjoyed a spectacular breakthrough season last term, hitting 15 goals in 30 Ladbrokes Premiership games.