Robert Huth's move to Middlesbrough is understood to have hit a snag.
The 21-year-old Germany international has spent the last two days on Teesside undergoing a medical with a view to completing a £5million move from Chelsea.
However, it is thought the proposed transfer could fall through after the two parties encountered a problem.
Middlesbrough were not commenting on the matter tonight, but new manager Gareth Southgate will be hugely disappointed if the move does not come off after reaching a verbal agreement with the player last month.
The fee and personal terms were agreed, but the player's involvement with his national squad meant the deal could not be finalised immediately.
Southgate will continue his search for reinforcements with a series of targets in his sights, but in the meantime, will continue to come to terms with his new role.
The 35-year-old has gone straight from captaining the side in last season's UEFA Cup final to the top job at the Riverside Stadium, and admits several of his players are still getting to grips with his new status.
Southgate said: 'They are not all calling me 'Gaffer' yet, and I'm not
insistent upon that either.
'That's very difficult for lads that have played with me - Ugo (Ehiogu) has played with me for the last 10 years.
'But I want to help them achieve as much as they can in their careers now, and it's very important to me we push forward together as a club.'